I guess it's not so much about paying but rather more about finding a shot engine that you can glean the parts from. I'm sure you could find a badly knocked about unit that will be your donor.
Keep trawling Gumtree and I'm sure you'll find one in a week.
Cheers, BB.
I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.