Hi Brummer and welcome to the forums!
I guess, "where to start" will depend on a few things. How large do you want to go? How much are you prepared to spend? What type of heat press? A roller press is mainly suitable for fabrics, a flatbed can be used for other substrates as well. What are your requirements for a printer? Format? Speed? etc.
GJS Machinery in Sydney has a couple of different models of heat presses to offer, including Geo Knight Maxi press used by some forum members. They also have large format printers and loads of good consumables and blanks.
Large heat presses usually are shipped in as required and second hand ones come and go very quickly to those in the know (I love my monti antonio 90, 900 x 1300mm shuttle)
It's much easier to find a large format printer - either new or second hand. You can get dye-sub Roland, Mimaki and Mutah printers and consumables from a variety of sources - try Fuji Sericol, they have a division specialising in large format dye-sub printing.
If you are ever in Melbourne or just have any questions to ask, you are welcome to get in touch and I'll take you through the ropes of the process
Good luck,