Unit runs about 50-100, cost to install starts about 150+.
If it's a mid to late 90's car w/o alarm, may be easy enough to do it yourself, but only if you're brave enough and can read instrutions, are good w/ your hands and do not have a bad back... hehe
Bought a unit w/ remote start/keyless entry for 50 at CC recently, installed on a 95 camry
myself, works like a charm. total cost is 50 + 18 for a multimeter + 3 for a crimper/wire stripper.
I already had some solder and soldering iron, etc.
Took about 2 days, some homework reading the instructions 2-3x, and planning it out, etc.
So basically, starter works by pressing a button 2x to start, it is set to run for 12-15 min then shut off automatically, you can adjust to 20 or 30 min, depend on model. You can't drive car w/o key. To drive car, stick in your key into ignition, turn it to ON, but do not crank it. Step on brake to disengage auto-starter, engine still runs, and just shift gears and you're driving...