Eric-Almost any inexpensive timer will work. I found a deal on 2 timers for 7 bucks at a home depot. They work excellent and can be adjusted in 5 minute incriments.
If your concerned about the timer being able to run the ballast, check the amperage rating of the timer. Typically they should be able to handle several amps. Some of the better ones, up to 15-20 amps. I just checked mine and they handle 15 amps residential, 8 amps tungsten. Basically, I wouldnt put any light over 8 amps on the one I have because of the heavy amperage requirements to fire them up. HTH