I own both and use them strictly for mid bass only subs. Prosub 1000 on my center channel (40-80Hz) and the Prosub 800 on rear channels (50-80hz) Both subs drop like a rock on anything below 35hz so they are best used as mid bass modules and nothing else. Instead of going with cheaper subs, I would look at spending the money not on a Prosub 1000 and either going the DIYer route for more slam and output (check out the DIY sub kits at Parts Express dot com or look at the entry level SVS or Hsu subs).
Going cheaper would be a waste of money because after a short period of time you will wish you had saved up a tad longer and bought a better sub instead of throwing the money away on a lesser sub.
Going cheaper would be a waste of money because after a short period of time you will wish you had saved up a tad longer and bought a better sub instead of throwing the money away on a lesser sub.