You want to talk enclosures, then let’s start talking Folded Horns and Transmission Line design theory… Wanna talk about some output gain!!! LOL
NE Ways, back on topic…
If you’re on a budget get what you can afford to start out with. We all started with crap before we had $$ and the knowledge as well as our tastes in audio developed.
The “$120 subs that will blow your socks off” are going to be crap, bottom line. Get the basic speakers and HU for now, then look into saving for a decent subwoofer and amp; something like a Kicker L5/7 or Rockford Fosgate.
There are a lot of people here who will say that everything is crap besides big $$ stuff. Do what you can afford, do the research into brands, quality, reviews, etc before jumping into anything, “deal” or “no deal”.