I don't know what your budget is, but www.partsexpress.com carries plate amps. You can pick up a 100W amp for $90 + s/h, and their prices (and power) go up from there.
Dorian I have a 100 watt plate amp. The only thing wrong is that the auto on off feature quit working. You have to turn it on and leave it on or manually turn it off. A little inconvenient but it works great. I would part with it for $50 shipped. Let me know.