My advice? If it's going to cost you, you could do everything yourself for a fraction of the cost. Typically Glocks are awesome unless extremely abused and overworked. I have Glocks that are going on ten years or older, but I maintain them well on my own and keep plenty of spare parts. My main concerns would be the magazine followers and possibly the springs. The previous posts and recommendations are not off base...but if you have had no issues with your Glock pistol thus far, I might suggest getting the armorer CD, a few spare parts just in case (at little cost + shipping), and run your Glock pistol like you always do and be ready to solve an issue if and when it ever does occur. With most Glock pistols....over-thinking things is always a possibility. For your reference (as usual), I'll direct you to one of the web's best resources other than the fine folks you'll come across here.
http://www.geocities.com/rhummer/uno...pdf_format.pdf