There is a link to a full write up on how to do them in my signature, I used some of the crappy repro chinese gauges for the bodies and fitted 3 3/8" speedhut gauges to them. I looked at the GPS unit but opted to get the standard one for a little less money. I then used a speed sensor off a VFR750, I had to thin the body of it 0.1" so it wasn't too tight in my forks. I tried a speed sensor for an acewell that plugs into the standard speedo drive, but it didn't work. The gauges cost me just over $300 shipped to Australia, the speed sensor cost me nothing because the local bike wrecker owed me a favour. Then there was just the time to fit it all up. I reckon for the results it was well worth the money.