The more tubes used in an amp will give it more power. Also the type of tube used will increase power. An EL34 tube is about 25 watts and a KT88 is about 35 watts. These Quicksilvers are nice amps within your budget and you can use different type tubes to change the flavor of the sound to your liking!
http://quicksilveraudio.com/products/midi-mono/
http://quicksilveraudio.com/products/midi-mono/