Hey D, welcome... (yeah, I've from Iowa too, but just a little further away than SirQuack)...
Anyway, my first home theater (going way back) had 2 subs in it that were, ahem, a "lesser brand/model". Actually they were basically just some cheap subs that seemed to "do the trick" for me and I was happy with them. Of course, I had a bunch of mediocre speakers to match. When I got my Axioms I didn't want the sound to be spoiled by a poor sub, even if my subs could shake the neighborhood, so I upgraded that as well.
Now I am in approximately a 10x15 room (with odd dimensions) with M60 fronts, VP150 center, QS8 surrounds and an SVS 20-39 PCi sub (12" - 350 watt that they recently discontinued). If the Axiom offerings at the time would have been a little "stronger" I would have gone that route, but that is another story...
I could easily get away with M22 fronts for the room size and still have great sound. The M60 fronts were bought when I was in a much larger non-dedicated room, so I needed more speaker than a pair of bookshelves.
As for the sub, holy crap Batman... Night and day difference. Sure I went from two 10-inch 150 watt subs to a single 12 inch 350 watt sub, so there was a little more power at my disposal, but wow. The quality of the sound was the best part. Yeah, I can still shake the neighbors' houses, but there is so much more to LFE than just rumble, and a quality sub is really important.
Now, I fully understand budgets (although I usually blow them on things like this) and making sure that the wife is on board with everything, but I just wonder how much you will be missing by having, no offense, a crappy sub in the mix. I only say that because I was there myself. You could end up not only missing out on all of the LFE benefits, but also end up "muddying" your overall experience. So if you really can't put a new sub into the mix now, be absolutely positive to put one into your plans for the future and hold to it. Don't just settle for a sub that seems "good enough" when you aren't really hearing a quality sounding sub.
