Those black face Palomar 250 and 300 amps are cheap class C throw away amps. Used and working 50-75 is fair. Brand new they are 109-149 depending on where you look. The best of the breed are the blue face Palomar 250's, they are class AB with some filtering.
Palomar Elite 250 Linear Amplifier, DNJ Radio
The number on the front is more of a model number, not wattage number. As stated, those finals are getting expensive. I used to buy the Elite 300's for 48 bucks each by the case, I could double my money easy in 6 weeks.