You'll never learn if you don't give it a shot, if you F*** it up, you're out $10 big deal...
The purple peel is b/c it was sh***y tint, not b/c they did it wrong
The best tint I have found for diy is 5% and the tint at the autoparts places isn't bad quality, Ive had it on my wife's Astro for almost 10 years now...