I have an old big and white Game Boy but I have no idea what is going on in here. People mod Game Boys?
Modify old ones to be back lit, color mod it to your preference and run a cartridge that has flash memory and emulates a number of roms.
I think
Yeah, you can mod GBs. The biggest mods are making them backlit and improving the speakers. Otherwise, the rest are just aesthetics or small tweaks for personalization. The old GBs can have backlit screens in any color (since they were monochrome anyway).
And the reason krikkz's products are usually leagues above anyone else's is for ease and convenience. His Everdrives can utilize microSD cards, so all you gotta do is drag and drop the ROMs into the memory card, then plug the card into the cart and voila.
He tests them a lot as well, so they usually have near-100% compatibility. If there are any issues you can report them and he might include a fix in a later patch. They might seem expensive, but they're definitely worth the costs.
I think the only games that don't work with the Game Boy Everdrive are those that utilize the RTC, and the only ones that come to mind are Pokemon Gold, Silver, and Crystal. He said he might be working on a new PCB what will have a RTC, but it's not a priority since he's not a Pokemon fan anyway.