It is worth checking out used fitness places for the adjustable dumbbells Rydra recommended -- I got a new set of powerblocks for about 50% off at a Second Wind (that store had a fair amount of new "accessory" type stuff to go with the big machines). I had to get a cab home and carry it up to my apartment in three trips, but it was totally worth it: they go up to 50 lbs in 5 or 2.5 lb increments, they're well balanced, and they're super sturdy.

Going on the last day of the month may help you get a lower price because they have month-end quotas -- I remain convinced that the set I got was not supposed to be on sale. :)