There is a reason for that - both the Firecons and Jumpstarters were extremely simple toys that were marketed around a gimmick. It is hard to find either of these toys with their mechanisms intact which affects their value greatly. Not to mention that they were both made in ridiculous quantities and never featured in the cartoon so they shelf-warmed badly. To quote the Transformers Wiki "Jumpstarters were made in sufficient numbers to fill the toy boxes of the entire known universe." If both toys were short-packed and in limited quantities, it may have been a different story today.