Not that I'm against bi-amping, but what has brought you to the conclusion you should be doing it? Because if you've been away from playing or just not really keeping up on gear, the capabilities of a lot of stuff today dont really require it, because people are doing more 2 and 3 way cabs with good or at least decent passive crossovers. So biamping makes the most sense if you're looking to do parallel signal processing on highs and lows separately (for instance, dry lows and chorus, etc... on the highs), or if you have very specific tonal goals.
The reality is that most bass cabs these days are already "full range", meaning they cover pretty much anywhere from about 50hz to about 15khz, give or take a few. So you end up with 2 cabs that rather than covering "bass" and "treble" respectively, are just slight variations in response over the same general range.
Which is to say long story short, if you just want a hellacious sounding inexpensive cab, just go find a single SWR Goliath III or IV for about $350 and be done with it. If you need something lighter/smaller, you may have to get more creative, and just try as many different amps and cabs as you can get your hands on.
For instance, I have 2 out of production Genz Benz "Uber Quads" which is a 60 lb cab with a 12, 2 8s, and a tweeter, and a passive crossover between all 3 sizes. it handles 600w and has a range of about 45hz to 18khz. So there's not much need for biamping unless I wanted some ridiculous lows and added an 18 for stuff below about 100hz. Now, I DO like that really deep sort of impact, BUT it's way more practical to just double up on the uber quads and have 1200w of power handling to play with. It's not quite the same, but I can have my rig up and running on a gig in about 2 minutes. 2 cabs, 7 pound amp, power cable, and 2 speaker cables.
Anyway, instead of skipping straight to "I need to biamp", you should figure out what your actual volume, tone, size, weight, and cost criteria are, and then go try as many things as you can within an hour or so of where you live to see what might work best. If you're in Gainesville, I have to imagine there are a number of music stores to go check out.