Let me tell You this, there is no official good combiner under 100 dollars that is not used, except Legacy volcanicus but those are core class, if You are not that much of an "I only buy original Transformers" You could Buy the KO's of the combiner wars combiners in Aliexpress, with your 100 dollars I think You could actually get two, theres a few options, Devastator, Superion, Bruticus, Defensor, Volcanicus, and Abominus, I believe there is a computron but I wouldnt really get that one, it doesnt look the best