Don't worry about those specs. Subs are supposed to do only low bass, say from 80 - 100 hz down. Your main speakers will takeover from where they let off.
As for two subs, it can be an advantage in large rooms, but with your budget, I question it's inclusion here. Plus, I'd rather one great sub than two mediocre ones.
Since good subs can cost money, and our tastes lean towards a bass heavy music, I'll shoot for the upper range of your budget. I'll dole out most of that to the sub and try to keep the rest in line.
I'd start with a
Denon 697[/u] STEREO receiver for $250. Yes, it's not five channel but it is a fine, powerful two channel unit with enough features to satisfy anyone. Oh, it's refurbished but many of us, including myself, have had exceptional luck with this place. ...and it's normally $600.
As for your mai speakers, a pair of Sony SP-FS52 speakers should serve you quite well. They have had quite a it of really, really good reviews here lately and I've heard their little brothers. I was impressed. Please note this price is for each speaker, not a pair.
Now for the sub. This is where I'm putting most of your money. Yes there are cheaper ones out there but with subs, you get what you pay for. I'd recommend either the Hsu VTF-1] or one of the SVS 100 series subwoofers. For your tastes, I'd probably go for the PB-1000 since it goes louder. All three subs come in around $500 but with either of these (and the rest of this system) you'll have some truly impressive 2 channel sound.
All this would set you back about grand.
If you want to come in lower, Accessories4less has a Denon 397 for $150 and there's a BIC F-12 subwoofer that sounds better than any $200 sub has any right to sound, but it's still a far cry from those Hsu/SVS subs. I'd stick with those main speakers, though. That shaves about $400 off my original system.
Good luck.
Just my opinion.