I have a rattler keyless entry system, and it was better than the stock unit on the old Mystique.
Here is a link to a rattler remote starter with keyless entry. I had Circuit City install my keyless, and they did a good job. Also, I felt that the $65 to install the system was reasonable. It will most likely take them a couple of hours to hook it up. I'd say that it would cost around $170 to have it installed. Also, make sure that you get all the options you want, like parking light flash and horn honk hooked up at the time of the initial install, otherwise you'll need to pay another $65 plus parts to have them installed later.
Hope this helps