my 2 cents:
I did buy an 03 GT 6-speed 3 years ago with 165K miles, has been a blast and running so good for 3 years. So, don't worry about the milage.
Look at the timing belt, it is a ticking bomb, make sure it has been replaced in the last 5 years at most.
As others mentioned, ask about the clutch. the clutch job on these cars is an engine out job.
But don't let that scare you, almost every other job on this car is a very DIY friendly!
The car is very easy and fun to work on, and parts are cheap.
Drive it for couple of months stock.
Then invest ~$300-400 on an Injen SRI and a catback exhaust, and it will transform your driving experience (not faster, just more fun).