Personally, I've had both Xerox and Canon equipment and I'm now using Konica Minolta. It sounds like, based on your budget, you are looking at getting used equipment. I don't know how much you'll be running (from your post, it sounds like there may be as many as 30,000+ clicks per month). Based on that, it tells me that you will probably be making a mistake putting in a used machine. You need to consider and look at a FMV lease along with a service/maintenance agreement. I don't know how things are done in Australia, but around here, for "print-for-pay" accounts, you are usually looking at a lease payment of around $700-$1,000 per month on a nice 50PPM machine along with a click cost of about $0.05 to $0.07 (USD) per image (including all service, maintenance, parts and consumables/toner).
We run two Konica Minolta Bizhub 6500 (65PPM) machines adn we usually do 40,000-50,000 clicks per month. Therefore, we are paying out about $2,000 per month for the leases plus about $2,500 per month for the service, but we're billing about $18,000 per month in color work. It works out pretty good, overall.
I've had only one used color machine and that was 10 years ago. Even though it was Xerox-certified and I had a service agreement on it, I didn't keep it very long . . . was just too difficult to keep it up and running in a production environment.
I highly recommend the color machines I'm using . . . and, I'd suggest you look into them. And, due to all the years I spent in the litho printing business before opening my digital shop, keep in mind that to run the two types of operations under one roof is somewhat difficult since it takes a completely different mindset when planning anything about the two routes . . . used equipment being a case in point.
As far as the carbonless, pre-perfed paper, etc., you shouldn't find that to be a big issue.
Hope this helps.