I've often said the usual economic laws of supply and demand don't apply to military surplus rifles. They made several million Lee-Enfield rifles and there's still more than enough of them floating around for everyone who wants one to have one, along with a spare. Most gun shops I've been into have several on the racks (one well-known Brisbane gun shop has nearly an entire floor given over to them) and the major Australianused firearms websites have several pages full of them; there's always heaps for sale at gun shows... you get the idea. I'd go so far as to say a bog-standard SMLE Mk III* is about the least rare centrefire rifle in Australia, along with the Winchester Model 94.
I totally get the prices on the HTs and XPs being really high - those things were never common anyway, and they're specialist rifles. But a standard-issue SMLE shouldn't cost as much as a brand-new hunting rifle, IMHO - even if they aren't making new Lee-Enfields anymore. They're not making Kodak Brownie cameras anymore either, yet they're readily available and very cheap despite the fact they stopped being made in an era when putting an astronaut on the moon was in that hazy spot between science fiction and actual possibility.