$25 is not bad at all if it is in good working order. At times you can find them free, however they can be in various states. A big thing is to turn it and listen for bits flying around inside. I have run into some that have been mistreated and the CRT housing was broken. Obviously that machine did not work.

Bottom line: Go have a look. A 400mhz is fine on the internet but if its a 700mhz you have a hard to find model (I've never found one anyways).