High David, and welcome to the forum. Sounds like you've done your research and have planned a strategic evolution into the field of astrophotography. I'm no expert but going from the gear other users on here have your gear is more than exceptable, especially since you are just starting. I have a HEQ5 pro and they are a great mount. You mentioned checking it, I presume you mean on a plane if your travelling? These mounts are quite heavy, approximately 15kg i think?) especially because you need counter weights to balance your photography gear. I'd be surprised if you could check it on a plane without having to pay excess baggage, but I could be wrong.
But anyway to answer your question there are several different surpliers that everyone uses, some I have links for below. Hope this helps, and good luck on your endeavours.
http://www.bintel.com.au/
http://www.andrewscom.com.au/site-section-10.htm
http://www.myastroshop.com.au/
http://www.australiatelescopes.com.au/
http://www.ozscopes.com.au/