i read that the alarm activation is a DIY type of thing?

Dude, you got owned. I paid about $400 on my last car (Ford Focus 2012) that's a bit bigger for one of the best tints you can get, maximum heat repellent, professionally installed. Huper Optik, it's pretty cool shit. Your $800 tint is probably generic basic stuff.

http://www.huperoptik.com/en/automotive/

my tint guy charged me 290 for full 20% tint. windshield brow, and have the tint shaved on the main windows to avoid that half a centimeter untinted edge.

dealer side, i didnt get any options. the car already came with wheel locks, rear applique, emission, trunk mat, and delivery. total:$25,161

900$ for a 150$ tint job???????? thats crazy man!

Even Hper Optik Ceramic wouldn't cost that much... -_-