If you have any places near-by to you that do fiberglass repair or fabrication work, you might consider asking them if they would be willing to make you a couple of benches. Show them a couple of pictures and give them some dimensions and I'll bet they could build them for quite a bit less than Casita
wants for them. They are merely simple squarish open bottom box shaped components. It couldn't be an easier piece to reproduce as far as fiberglass goes.
I also agree, for as little as there is to these things, Casita's prices are way out of the park for what these things are. Probably not more than $10~$20 worth of materials needed to make them.