I noticed on Vanbar's website that many chemicals are out of stock to online orders also. I don't know if this is an increasing trend, as I don't deal a lot with Vanbar, but it always annoyed me in the past that I could usually bet they'd be out of something I wanted.
I don't want to sound negative, but I think much of the problem is due to the small size of the Australian LF market. Vanbar probably carries more stock than anyone else, to their credit. Smaller businesses usually have smaller inventories, and I noted the other day that Blanco Negro is out of some of their advertised lines of printing paper.
I tend to wait until I can afford to place a large order, then use B&H or some of the other overseas suppliers. But with the AUD so low at the moment, that hurts too; but I can usually get what I want.