I am having trouble sourcing a new Burial Register, do you sell these or do you know where or who would sell the registers?
I'm assuming you're referring to traditional paper (hard copy) systems.
Cemeteries & Crematoria NSW has a guide for registers here:
The article says
Cemetery operators can decide the best way to keep their register. For example, the register can be wholly or partly in the form of a computer database, or in documentary form. Specialised software packages are available that are used in the sector by some operators. Other operators use modified database software to capture the information
That suggests for hard copy systems you can set up your own, i.e. use a digital format template and print it or instruct printers to prepare something for you
Footnote: I remember trying to source the old prescribed registers in the late 1990s. It was impossible and we printed our own before moving to digital databases.