Your in luck. Now a days you buy good sounding stuff pretty much anywhere. Even Walmart. Example:
http://www.walmart.com/ip/Kicker-PT2...ifier/32983978
Under $200, all you need right there. Well, you'll need an amp kit. Which you can buy it there for $25.
Enough bass to sound nice. All in one box.
Want more of a kick?
[ame]http://www.amazon.com/gp/aw/d/B007AQ2W6W/ref=mp_s_a_1_5?qid=1460293003&sr=8-5&pi=AC_SX236_SY340_QL65&keywords=powered+subwoofe r&dpPl=1&dpID=51hZI-BZ%2B5L&ref=plSrch[/ame]
Hell, just google "powered subwoofer car" or on Amazon
You can go and buy individual parts. But in the end it comes down to how much you want to spend.
Once you pick out one you like post up here. Just avoid cheap brands like Duel and Boss. They work ok, but they tend die quickly.