Rabbit: you don't need a cage; rabbits can easily be litter trained. (I have about 10 or so rabbits, but they're all outside in cages.. well, 10 or so are in cages... there are a lot of escapees that hop around the yard.)
Guinea pigs are pretty lame.
You're on the wrong side of the country for me to help you out... I'll be at a farm auction tomorrow. Last week, a few area breeders were dumping their excess animals that weren't "show quality" or whatever... Most were really cute! They'll be dumping them onto the market for the next 4 or 5 weeks here. Baby bunnies and guinea pigs at this time of year typically sell for between 25 cents each and $2 each; depending on how long the auction has been going when they get to them. Of course, they are sold by the box; so sometimes to get a particular one that you want, you end up buying 4 or 5... We did that a few times and just gave the extras to kids in the neighborhood. I'm hoping to get some rollers and tumblers tomorrow (pigeons that do weird things while flying), and perhaps some turkeys, goats, or whatever I find that I can't turn down for the price. Sometimes it's hard to resist, such as a beautiful bird cage with two young (3 months old at the most) cockatiels for $10. Other times, I've bought animals simply for the cage that they were in. Water bottles for rabbits run around a few dollars each... if someone crates up a rabbit and includes a water bottle and a bowl, then I jump all over it if it goes for under $2... I just let the rabbit run wild when I get home.