Thank you all for insight.
Budge I'm guessing $1500 but thought about only one?Millercarbon suggested 3-4? That would change budget considerably.
No, it doesn't have to be expensive. All the comments so far are people following the old method of using one, or sometimes two, really big and powerful subs. Using one or even two means they have to be big and powerful. Using 4 means they can be much smaller.
But that's not even the biggest benefit.
The real problem with subs, which you will discover real fast if you try, is lumpy, uneven bass response. This is for every sub made and there is no way around it. This is why I said "impossible" above. Its simply a fact of physics.
So here's what happens. You stick the sub somewhere. Does not matter where. You listen. You hear more bass. Great. You're so happy. But then you notice its one note bass. Above and below that one note it drops off real fast. So you move the sub. Now its a different note. Turns out there's a whole thesis research paper study done on this with exhaustive measurements proving it is impossible to achieve even bass response with just one sub.
Or even two. Or even three, but its getting closer. Four and you are there. More is even better, but not a lot. Four is the sweet spot. Nice even powerful bass from 4 not very big subs.
That's what you want. Read the papers. Save your money.