wont start on 2007 Chevrolet Avalanche

my 07 1500 LT avalanche has 100,000 miles,wont start battery good alarm still working,makes a click noise when i try to turn it over,i even tried to jump start it,

2 answers
Same problem,137,000 miles, good battery, new battery. It just clicks. Did you discover the problem?
Have you tried to put on a new starter that's what i would start with first. you might be able to even take it off and take it to someone that rebuilds them and you might be able to save a few bucks