This guy for Pnp 7m ms3 pro set ups -
http://perfecttuning.net/en/
Parts and tuning are totally real cost!
I went with a used SMB v3.57 Megasquirt 2, sold the MS2 board and bought the MS3 card along with the expansion so i have a ms3/ms3x - just the box(ecu) was around $600 total, wiring and sensors $$$, having a tune $$$, dyno time $$$.
But since this is a loving community, I was able to get a fully tuned based file from that website above and to date seven 7m's running it now. All because I was able to share the tune file that was shared with me.
No way you are doing this for less than $1500, but at that price you will have all the options you need. At this stage of the game, you are lucky to have options, when i started megasquirt couldn't even drive a 7m let alone run extra stuff,but as a MS user, its come along way and is still great bang for the buck.
And fyi - the Tuning Software is the same use by these guys: (most important of all - is the software good and easy to use, yes yes yes)
Freescale Semiconductors
Megasquirt Community
ProEFI
Monster Products
BigStuff3
Harley Davidson
Buell
Factory based OBDII
Dynojet - Power Vision, Power Commander
or
I'll sell you my box no sensors or wiring ... But I'm not offering that here, that would be against the board rules .