That's the funny thing about Spaceballs. Brooks got George Lucas' permission to parody Star Wars prior to filming under one condition - that no merchandise be produced from the movie. This is why Brooks thought it was funny to include all of the scenes of Yogurt trying to sell Spaceballs merchandise; none of it existed off of the set (not legitimately, anyway).
Lucas knew that the merch would sell really well lol. They could always do a Spaceballs prequel lol. I just wish the animated series had been better, they had some of the original cast but it just wasn't that good. Every since big budget comedies with giant sets went out of style Mel's movies just aren't the same.