Inexpensive but decent 8" subwoofers

Not sure why you’re disregarding the SVS 3000 Micro given its price, performance, built-in room-correction software, and risk-free 45 day trial including shipping both ways, but best of luck whatever you choose. 

Well the most expensive ones on my list are 500 USD, but SVS 3000 micro although it looks nice, is listed at 900 USD. 

I am sure I can get it cheaper used, but that doesn't mean I can get it at sub-500 prices probably.

Check out the scratch and dent or blemished section at SVS. 

Found in the outlet from the dropdown menu.

My 3000 Micro supposedly has a couple blemishes, I sure can't see them. 

They are running about $750 though. 

I have a Monitor Audio Bronze Sub sitting in a box right now. I'm not sure if it's an 8". Sounds really good. Lacks the mobile app adjustments the SVS has. 

I could put it up for sale here if you're interested. (way under $500) 😊

The smaller B&W subs have never dissappointed.  Honest, musical, good performance for the investment.