You might be able to swap motors. I changed out a 3.5 HP on an old Toro in January with a 6.5 HP Greyhound from Harbor Freight.
It ran great last year from January until April for the few hours I put on it. I have not tried to start it yet this year as I have been playing with an old Ariens I managed to get for a good deal.
I was doing my yard plus a couple neighbors each time it snowed, so it got a fair amount of use.
They sell them at $179.99, usually on sale for $129.99, sometimes and was recently for a while on sale for $99.99. You can find 20% off coupons around too, so that ends up being $80 for a new engine.
These are considered Honda clones. They are basically copycats of the Honda GX 200 design built by Lifan. There seems to be a lot of good things said about them online and not much bad.
We would have to know a little more about your current machine and it's engine to know how easy of a change it would be. Some snowblowers use 2 pulleys on the engine with gets a bit more complicated.
For the old Toro 3521 I have, it was a simple and easy change. All bolts/belts/pulleys were direct swap. My only problem was the chute crank rod was in the way which I solved with a 2x4 spacer as I was kind of in a hurry.
http://www.harborfreight.com/engines-generators/gas-engines.html?order=position&dir=asc
This message was modified Oct 7, 2010 by Shryp