From your desktop?
Honestly, what you're after is a road full of disappointment and wasted money in my experience.
The cheap stuff you're looking at is for short term use or comes with a lot of caveats. Sure you can get it to "work" but it's fickle, has issues, never works how you want unless it's a dedicated solution. There is no cheap, easy way to do this. Yes, Chromecast works, but does it? If you need to constantly leave that big gaming rig running how efficient is that? And if you stream local content like a ripped blueray, oh boy do I have some bad news for you. All these cheap solutions are for temporary use and a secondary function. I have never seen anyone use these systems long term with real success. Students can do it in a dorm but they usually don't mind fiddling (they're cheap) and it's in a single room. If you get home from work do you want to spend 5, 10, or even 20 minutes getting it to work properly or do you want to pop it on and start watching?
First things first...
Wireless in my experience is going to be an issue due to bandwidth. Yes, I know companies claim "1800Mbit!!!!", that's adding all the radios inside together and it's complete marketing B.S., besides the fact that wifi receivers don't really work that way, usb adapters are even worse. The truth is, if you actually exceed 300 or so Mb in usable bandwidth you're doing exceptionally well, especially if it's consistent. Just getting a faster, more reliable connection than good old 10/100 hardwire is an accomplishment at times. Keep in mind, I said consistent, which is the problem. In my apartment just going through two walls and 30 feet distance I went from what should be a 400-450MbMb (?) connection when close to the router down to around 20Mb. Transferring a 2GB file took the better part of an hour whereas on gigabit I could do it in 3 or 4 minutes at most. Keep in mind most usb adapters are even slower, few get over 400Mb and are usually either 300 or 150 unless you spend quite a lot on it and that's assuming the router supports it. Don't forget, this is before you encounter external influences like neighbor interference or worse, someone else using the same wifi. Got a spouse or kids who use it while you stream, good luck.
Wifi is good for internet, you download in chunks, it has variable resolution and quality, downscaling upscaling, it's compressed and it caches as it goes so any up and downs get masked.
Local streaming has a buffer but that's about it. If you stream a blueray rip it's going to send that same quality and expect a consistent connection. Wifi is f'ing TERRIBLE for transferring and streaming large files, the rate can jump from 25Mbit up to 400 and back down again simply because someone walked in front of the router or tv. What you watch online is highly optimized, your system won't do that, once you lose that and try to stream anything you download or rip all bets are off. You may have seen TP and I discuss 10Gbit connections to replace our gigabit hard wired connections to our media systems, this is why. Gigabit is actually fine for streaming local stuff, we want faster for moving files around because while you can stream a DVD over 2 hours, you don't want to wait that long for a transfer.
The solution
If you stick with it odds are you will end up where most people who do this end up, building a dedicated media player and/or file server. It sounds extreme but it cures a lot of issues with data transfer and if you use it daily, it can actually save you money compared to just casting. It also makes your desktop faster. I assume your desktop is a big, built up gaming machine with big drives, it needs to remain on anytime you want to watch something through it and it's power hungry.
This doesn't need to be expensive, my first media player and file server was just an old computer but these days people use Raspberry Pis. Personally I'm not a fan of that, Pis are a hassle but have their uses. I recommend looking around for a small Intel system, Celeron or Atom is plenty, even old first gen Atom is perfectly fine. Laptops are fine, though a small form factor is better. Yank out the optical drives, use onboard graphics disable anything not in use, at this point it will idle in the single digits for power once the drive spins down. If you want or need to build something, I like to use use 3rd gen core I5s, they run about $30, the motherboard can often be found at similar price. Another good option is Intel Nucs and similar, a cheap alternative is Lenovo M92p and M93P, you can find these on Ebay for $100. These and the Pi work for streaming but for file serving they are not as good as a low power SFX/ITX setup where you can pile in all your drives and offload all of that from your desktop unless you spend the money on a single large drive as they lack connections and power (watts) to run it all. For media player remotes I use old HP or Dell media center remotes (infared), they're plug and play and run about $15 on Ebay but you can get cheap Chinese radio ones for $10, just be sure it's plug and play and not some old infared Chinese junk if you go cheap, those are not plug and play. Then load install Kodi and point it at your media folder. You can get all of this, for not much more than the cost of a nice wireless Nic and a lot less than a good router.
So how does it save you money and speed up your desktop?
My desktop uses about 75 watts at idle (more if I had my big drive in it), with screens it's even more, but I can turn it off at night or let it sleep, meanwhile my server runs at a consistent 15 watts and I can access all my files from my laptop, media player, phone, etc. at any time, anywhere. This also means I don't need large drives in my desktop, allowing for a smaller box, smaller power supply, fewer parts and when I need to rebuild it, very little data is actually stored on it. Backups are faster since that data isn't there, I can offload large downloads and uploads to it even while I game, there's less data indexing going on since none of it is stored on it, it just makes for a much simpler desktop. I keep my server drive spinning (no power down) so it accesses faster which keeps it closer to 25 watts but that's because I prefer the faster access times. It's still less than running the desktop which would be running the system plus that drive 24/7. It saves me about $50-$75 a year in electricity by powering off the desktop and I can't imagine life without it it's made things so much easier.
