Spike's are having backlogged with orders. I seen people been waiting more than 3 months. Your best bet is to look from aimsurplus.com or gunbroker.com for the stripped lowers. Then buy separately the PSA LPK, ALG Combat trigger, KNS Anti Rotating pins and Buffer Tube Assembly. I believe it costs much less.
To be honest, i did buy 1 Spike's enhanced lower without stock with color fill early this year, in January maybe. I had to wait around 70 days, u can imagine if u order now, also they increased the prices too. Costed me $340 after discount. Then i built another lower with the parts i mentioned above.. saved me a lot compared buying from Spike's.
Hope this idea helps for your references.