Something in the realm of 3000 joules is the right idea for the right cost. .These can be found anywhere up to Hundreds of dollars down to $20-30.... You get what you pay for but keep in mind that some of the super expensive sell on their "name" and marketing fluff, and some of the cheaper ones don't offer the filtering that the $$$ ones do.
I've found that the $60-80 range is a good target price... try APC, or Tripp-lite if you want a known excellent name, and something you know will work.
I'd also look into just getting a UPS, as they offer more out of the box in the way of line conditioning, and you get the ability to stay up during brownouts/voltage fluxuatiuons.