I went to Radioshack today to pick up some diodes for something else, and it just happened to be right next to the PC boards, etc. I remember reading about making your own FCD online and wanted to try it, but couldn't really remember exactly what I needed.
It is similar to the TwosRus FCD, which sells for $37. Heres the link if you plan on trying it. Only thing I dont like about the DIY method is the "setup" on the bottom. I have a pressure gauge, but I'm not sure how I'd apply 14-17 psi accurately to setup/calibrate the FCD. I wonder if I'd just to be able to use the values for resistance posted on the site and use that instead, making it alot easier since you're only using an ohm meter.
DIY FCD
If you're on a budget, or just dont want to spend that much money on a FCD, I would just buy a potentiometer for a few bucks at radioshack, and wire it in right near the ECU. That way, you wont have to worry about the project board and all the soldering on the board. Just wire it up near the ECU where its weather safe and out of harms way. Its not like you'll need to mess with it often.
Total cost will probably be around $4-5, since all you'll need is a pot and some wire, and BGB to know the ECU pinouts.