I'm about to give MegaSquirt a try on my VR, which will be going turbo in the near future.
All the bits are ordered and I'm just waiting for them to be delivered from the States.
The full kit of bits (that you assemble yourself, but you can get ready built for a bit more) works out about £250. Thats for the v3 mainboard latest processor, dual map sensor, EGT, the simulator board for bench testing, the lot. But it will need fitting and setting up after that.
The only thing I've found so far that it doesn't do yet is sequential injection (ie pulse each injector separately). It's being done but not finished yet. This will be in the form of an add-on board for the existing system, so a retrofit should be OK.
It's amazing value..... but only if it works. I've read up loads on various sites about different projects and, on the whole it all seems positive. Maybe a bit tricky to get going with the 60-2 wheel on the VR but I found a few that have done it.
When I get my kit I'll start a writeup on progress install etc etc.
Somebody recently recommended MBE for my project. That looks very good, but starts at about £700 plus fitting and setup etc. So quite a big jump.