Yeah, Memory Express is probably your best bet. Are you looking to go custom, or pre-built?
EDIT: Also, what games do they play?
EDIT2: Made a parts list exclusively at Memory Express. Note that you can probably price beat quite a few items/find them elsewhere for a better deal. The regular Ryzen 5 3600 is out of stock otherwise that's a better choice than the 3600X. Windows 10 licenses can be bought elsewhere for cheaper than the $100ish that they charge.
