cheap 2 way pager alarm can be had for $77, and a really nice one for about $150. the actual cost of labor is about $60-90. everything over that is mark up / profit.

i paid $190 for my 2-way pager alarm w/ proximity sensor, dual shock sensor, backup battery, 3 sirens total, fuel kill, starter disable, remote start, keyless entry, hood/door/trunk sensors. took me about 4 hours to install myself.