I'm currently training, in an Ecoupe 415-C, for my Light Sport ticket. In fact, I soloed this plane two weeks ago. (I'm Post-Polio, and a wheelchair user, so the rudderless Ercoupe is perfect for me.) I'm seeing a cruise of about 85-90 knots, indicated, on 75 horse-power. With a fuel burn of slightly less than 5 gph.
The 'coupe is a delightful airplane to fly. The "stalls" are a real trip.
However, finding a good one, that's LSA qualified (meaning a model 'C' or 'C/D') for less than $30,000 may be difficult. The one I'm currently flying is for sale (on a leaseback agreement) for around $20,000. But it has a high-time engine, and a very basic panel.
Keep inmind that all later model Ercoupes, begining with the 'D' model, are not LSA qualified. Also, if it is a 'C' or 'C/D' model, that has been upgraded to a 'D' model, it also is not LSA qualified.