For a great variety of choices including ages, color or sex, check out the Greater Androscoggin Humane Society. https://www.facebook.com/gahumane They are in the Lewiston/Auburn area and have over 170 according to yesterday's newspaper article. Looking at their website (not Facebook page) they charge a mere $25.00 NEUTERED! That is a great deal. Apparently February is "Adopt A Rescue Rabbit Month".
Or if looking for guinea pigs, in Kennebunk they recently took in 73 cavies. March is "Adopt A Rescue Guinea Pig Month". It is the Animal Welfare Society at http://animalwelfaresociety.org/adopt/adopt-small-animals/ I think mostly just males (boars) are available until they know that the females (sows) aren't pregnant.
They also have rabbits if you are in southern Maine or NH.