My 98 Contour SE (6 cylinder 2.5 L) has 65000 miles on it. But a dealer told me after an oil change

that there are some small tiny cracks on the edges of the inner side of the serp belt. He reccommended replacing it ($100!). The service manual did not say you need to change the belt at at only 65000 miles. But Murrays Auto parts store has it for only $11 for 1 year waranty and $17 for lifetime warranty. Did anybody repalce the belt by themselves? Do you need special tools?
Thanks!!!
huacat