[H3N51N]

Looking to get into this line. I'm hoping to get all the Buster Machines since the DX ones are so expensive & take up quite a bit of room. I'm glad they managed to fit all of them in this tiny little format, which brings me to ask: has there ever been a Sentai Mech/Ranger Megazord that you wish was made but hasn't been? I mean, how popular is this line of toys? Do they get enough satisfying results to justify making more? Do they leave out some mech/zords for various reasons?