500 is a rather tight budget. You should look into your local second hand market if you want to make anything decent with that budget. I honestly think that buying a per-owned and per-assembled PC is better nowadays, because of preposterous GPU prices. For second hand PC I would recommend these items from Amazon.

Ryzen 3 1200/2200 - $80–100

A320 boards - $50

8gb ddr4 ram (any brand) - $30

M.2 ssd (256/512gb) - $30–50

CPU cooler (hyper 212) - $20

PSU (at least 450 bronze) - $40

GPU (1660) - remainder of your budget if you can find one on eBay 😂

Or you can just get this iBuyPower one.

The total cost really depends on your local market but this is what I would recommend paying for. Hopefully the cpu prices will drop once the b450 boards release the bios update for the 5000 series. This theoretical system would be still good for 1080p gaming (with this tight budget I’m assuming you are pairing with a 60–75Hz 1080p monitor).

You can also try Ali express. At the time of writing:

CPU (Xeon E5 2650 v3) - $82

Mobo (X99 Jingsha m-atx) - $70

Ram (8gb ddr4 ecc) - $30

M.2 ssd (welmade nvme 256gb) - $40

cpu cooler (snowman lga 2011) - $20

PSU (cooler master mpx5501 master watt) - $70. Sorry, I don’t trust Chinese PSU. Get this from Amazon instead.

GPU (rx570/580 4–8gb) - $150–250

So yes. You can build something below $500. But don’t think about gaming beyond 1080p and above 60 FPS. BTW, FYI some of the Amazon links are my affiliate links. I will earn a small commission from qualifying purchases.