I have owned the original GameMaker 1.4 Studio and now am interested in buying the PS4 export module for GameMaker Studio 1.4999. I don't see an option to buy that anywhere. Any help would be appreciated.
1.4 is no longer supported or updated and hasn't been for a couple of years now - as such you can't buy official licences for it either as they are no longer sold.
Even if you could, the lack of support means that any binaries the PS4 exporter made would likely be refused by Sony who would have since updated their requirements.
Also you can't just buy the PS4 module - you need to be accepted onto the PS4 by Sony before you would be eligable to purchase it from YYG.
If you are at that stage and have already been accepted then you need to purchase GMS2 and the 12mth PS4 console licence.