Take a look at the SPADforum here on RCU. The make planes from old signs and the likes. The do end up to be heavey and don't preform as well as a good balsa built plane.

My suggestion it to make contact with the local club and get some instructions. When you tell them your delima over the job, I wouldn't be susprised that a couple offers for a used trainer didn't popup at a price that would be way below what you could build one for. Learning to build and learning to fly without help is most likely going to lead to a much more expensive intor to the hobby. A good, known design 40 size trainer ( 60 in span) at around 5 lbs is what you should shoot for. Isuggest a good brand kit as it will have the hardware that you would need to buy on a do it yourself design. When you start buying landing gears, motor mounts, hinges, push rods, horns, nuts and bolts, etc, it can add up to more than a kit would cost you that had the stuff included. Again, most club members who have been flying for any time have a collection of these parts that you may be able to buy for a very reasonable price if you decided that you have to design your own plane.

Welcome to the hobby.

Don