I believe I got my from Brothersperformance for ~$90.00. Don't know how much cheaper you can get it unless you get it used, but then your gonna need some electrical connectors that come with the unit.

i got mine in the mail today, but i have a question on programing it for my gears.. i found my old/new gear ration on the chart they supplied, but they are all 1's and 0's and in the speedcall where your supposed to program it the numbers are 1 to 10... so how does this work??

The best way to get it set up perfect is to install it and then take it on the highway. Reset your milage for a 10 mile stretch of road and record what your exact milage readout was (example 9.2 or 10.7) You can have a friend in another car clock the 10 miles on their odometer to let you know. Then you go on the Dallas Mustang website in the Speedcal Forum and post up what numbers you have set now and what your milage was and they will give you the exact numerical sequence you need.