I'm running a home built that I made ~7 years ago. I out $900 in parts into the build and it still runs everything I ask it to.
I understand your concern about doing a home built rig. If you haven't done it before it can be daunting and frustrating. AS far as buying one before the prices drop--I get that too. In my experience, I am a catalyst of price change as in, whatever I buy today goes on sale tomorrow.
I haven't played the new u-boat subsim. I've watched a lot of videos on it and I can't say that the micro-management and overall style of it appeal to me. I'm much more concerned with realism vs how pretty it is. I'll be keeping a Very close eye on Destroyer: The U-boat Hunter though. That show a lot of promise imo.
Cheers!