Steam is currently doing a big RPG Maker sale in 2 parts starting today, the next part is on Feb 10th (Not sure what it'll be, my guess lots of asset stuff on sale since most aren't on sale).
Currently RPG Maker VX Ace is available free for those looking to get into development or using it for existing games to explore and learn from them (that a dev has given permission for). The 2nd option of buying it is something else, think you get a key to give someone possibly. It doesn't give steam cards, and it might have limited quantities of it being free.
RPG MZ is the most expensive since it's the latest, but MV (IMO) is far better and easier to edit and learn from since it's been out longer and has a lot more support. MZ you cannot edit animations without another program, and plugins I believe are encrypted, and the differences between MV and MZ are so little. For the cheap price, MV is a good one to learn to develop on if you're looking to create vore story orientated games. There's a lot of other people and devs who are happy to answer questions and try help when asked that use MV too.
