Check out http://www.daveswebshop.com/76dss_dish.shtml as a good solution since it handles the "D" shaped mount of Dish LNBs and hence is already set up for the right focal length (as opposed to the hacksaw technique). Buy a DP Dual and you're good to go. You can buy Duals off of Ebay, from internet satellite retailers or local retailers. Can't remember how much they are going for but I don't think much. This 30" solution is probably around $75 for Dish and LNB would be my guess.
Check out Greg Mueller's posts, he made a Primestar 85E 30" into a 129 dish, has all the plans. I tried an oval 75E with a dual Dishpro lnb and it was no better then my Dish 500 with a Dishpro twin, I found out from a retailer that oval is not proper for 129.
Since I live on the east coast, and my dish angle is so low, I hooked up my Channel Master 1.2 meter dish. I took the housing off of a DP dual lnb and it fits perfectly in the lnb holder. I get great reception now My lowest transponder level on my 622 is 78 with the highest being 108. It's ashame I have to waste this dish on a circular satellite. I will be changing it out with a 36" winegard so I can put my "micro BUD" back to use.
I am on the fringe and using a 6 footer ;0 heh I get quite decent signal. We are as im typing having a crazy lightning storm and i still have about 60-70% signal on most. some down in the 50's though. Normally i get full signal on a few and in the 90's-> 100's on the rest.