Welcome, your only problem (unless picking up a engine for little or nothing at all) is staying in the $150.00 range, just about impossible. Buying a kit for $150.00 today is remote, 2-3 years ago was common. A Chinese kit is about the cheapest way to go, unless you have a good mechanical ability and can build one. Best of luck. The last build, not counting the $100.00 for the bike was about $200.00, and that was over a year ago. This is what I built for the $200.00.