$600 is damn cheap for an alarm with remote engine start. I am currently looking to spend about $450 just on a remote immobiliser with a window lift feature, but will need to do a bit of shopping around.
Regarding the front door lock removal, it can be done (just remove handles and locks, putty up and paint the hole) but what do you do if the alarm fob battery dies or something? Normally you open the car, and turn off the alarm by some sequence, but that's no good if you have no locks...
Jack Travis, E-Series Acting President
1989 Ford Fairmont Ghia turbo/GL replica (underway)
1994 Eunos 800M
1990 Ford Laser S