Find out what's sailed in your area. Not only does this provide a supply of used boats but also a ready market when you're ready to move on. I've seen too many people buy some orphan and find when their ready to move on that there is no market for them.
Since you live in the midwest and the Flying Scot is sailed widely in the midwest, check out the Flying Scot Association website to determine where there are fleets near you. Even if you have no intention to race the locals will be able to provide valuble information regarding the boat and the used boat market.
Avoid heavy boats. The diference between a 500# and a 900# is significant when you're trying to get it on the trailor.