I really don't know where you guys are getting your costs from (OP is more realistic). While $6k is expensive - just looking at somewhere like stout tanks range you are at $600 just for a standard 14g conical that can only take 4 psi. Then to through together a small footprint cooling/heating system their peltier DIY kits sell at $125 each and you will need at least 2. And that only gets you the machined mounting plate, heatsinks and fans. You still have to stump up for 4 peltiers and a control system. Then sort out how to pull it all together to be able to ferment and serve.
Yes the Williamswarn is a overpriced in my opinion, but it is not something that you can DIY cheaply (but you could much cheaper than $6k but I doubt sub $1k)
Tho has made mw wonder how you clean the Williamswarn thought?