When should you change a timing belt on a 2000 Saturn LS2 v6?

It is changed every 100,000 miles at a very hefty cost. My dealer estimated over $1000 to change it. With the extremly poor Kelly Blue book value of any Saturn, I decide to do it myself or trade it in. NEVER EVER buy anything that GM has had any involvement with. Honda, VW, Toyota, Hyundai, Nissan and Kia dominate for a reason. They hold resale value and wont bankrupt you with repair costs.