While $300-$400 sounds like plenty caps and switches alone can easily push you over $100 (or even well over $200 if you go wild), then there's lube, stabs and cable if you want any of that. Up the switches to something more high end or boutique like Zeal, some krytox lube and some higher end stabs and suddenly you've spent over $200 and you haven't even bought a board yet so you will need to be a bit careful how you spend.
Take a look at the Novelkeys NK65.
Very heavy for a 65% and I'd argue a better design than the Tofu (I dislike tray mount), hot swap, RGB, fully programmable with QMK/VIA, you can get replacement boards if you damage it and it's under $200. It comes with decent, pre-lubed stabs, they had plenty of thick lube on the bars, might stand to add thinner on plastic to plastic spots but mine were perfectly serviceable out of the box (I did do a bandaid mod).
This leaves only switches and caps, I'd also recommend a magnetic cable to protect the port, not that it's an easy port to damage but it's just an added bit of safety for the port. As for lube, since they did the thick lube you don't need that (I use Superlube Dielectric grease), but you still may want something for your switches, instead of Krytox, try Finish Line Flouro Extreme(with ptfe), it's a lot cheaper, allowing you to spend the money on switches and caps, I use the HK Gaming caps on Amazon, you can get a 144(?) cap set of thick PBT for about $40. They aren't shine through but are thick enough to not allow light bleed so you end up with a very nice glow around the keys.
One warning about a switch tester, don't try a switch you aren't prepared or won't be able to buy, if you can't afford Zeal or get Bobas or something, don't test them. If you find a switch you want, don't settle for your second choice or you will just be buying them later. Test what you can and are willing to buy and continue to save if you need to to get it right the first time.