You can get the SuperMicro X9DRL-iF with 2x Xeon E5-2650 v2, 16GB RAM and passive coolers for $199 (link below). I bought this combo recently and they currently have 6 left.
I ordered the same fans you picked as well, so good choice there. For the RAM, you should pick higher density chips (e.g. 32GB) to maximize any future upgrade options. I picked up 4 32GB ECC LRDIMM for $50 each ($200 combined). Keep in mind you can’t mix LRDIMMs with RDIMMs, so the memory in that combo likely won’t be useful unless you go RDIMM.
Motherboard Combo Deal
RAM I bought - https://www.ebay.com/itm/32G-HP-712384-081-M386B4G70DM0-CMA-4Rx4-PC3-14900L-Server-Memory/202883114171