Here's a few scatter brained thoughts after a long day in the sun:
For 25 birds, I would just get a couple people to help and hand pluck them.
We raise about 250 freedom rangers and 40-80 broad breasted whites every year and we bought a featherbird two years ago. It's not exactly in your price range, but I figured I'd mention it. Maybe you can find one used? We bought the same version that we rented from our feed store for a couple years. It works like a charm. A 30 pound turkey will need most of the tail feathers and flight feathers hand plucked before putting it in the plucker, but I've seen it handle a 40+lb turkey after hand plucking the bigger feathers.
There are some good resources out there on building your own plucker with a belt motor and a 55 gallon drum. Look up whizbang plucker.
A couple times I borrowed a friends off-brand plucker that seemed to be made out of thin sheet steel. It was heavy as a boulder, and would probably not fit any size turkey, but it did work pretty well for a few chickens at a time.