I did the same thing except I spent like $4.00 on a peice of aluminum.eeeeek : I made one myslef for about $.59 and it wasn't hard at all.
Unbolting the stock mudgaurd is very easy. I then pulled off the tag light (it's on a couple of 'extenders') and mounted it where the reflector was. Then, I bought a pice of sheet metal from home despot, drew and outline of the plate on it and an outline of the plastic mounting point, cut it out, bent it, used the light's bolts to secure it and was done.
For good measure, I switched out to smaller turn signals, too. The entire project took two beers (two hours).