I´ve seen used engines go on Ebay for under $200. Sometimes entire bikes with no title in running condition for under $500 in my local classifieds. I scored one for $80 locally and having no previous experience and the aid of a Clymer´s manual, I was able to swap engines by myself with one full day´s worth of wrenchin´, So it can be done, cheaply! Hope it works out for you!