[Edit]... I realize that my 2c worth below may not be that useful in Oz, though I suspect the woodsies and other wooden shapes have been marketed down under as well -- they originate in your neighborhood, after all.
I glue double-thickness woodsies from Michael's Crafts.  Two rectangle packs (@3.00 each) nets 40 of each of a 2x1" 3/4x1.5" and 1/2x1" bases.  I cut the 2x1 bases to 40mmx25mm for vehicles.
Woodsies Rectangles: Online SupplierAlso at Michael's and other craft stores you can find a 52-bag of alphabet rounds: wooden disks about 1/4 inch thick and 25mm round (with letters of the alphabet printed on them).  These are about 3.50 a bag: and so, at .06 each, generally cheaper than 25mm fender washers.
I think the brand is "Lara's Crafts."
Lara's Crafts Alphabet DiscsWoodsies can be drilled with a 1/4" drill bit to counter-sink infantry, although I've struggled to drill a clean hole -- Dave is much better at this procedure.
Another solution to countersinking is to find thin sheets of craft cork, also at Michael's and other craft stores. This can be cut with scissors, etc, and more importantly, it can be punched with a hole punch.
Sand for flocking, although I started using coffee grounds (I have a variable-grind coffee grinder) and then moved to rice (through the coffee grinder) when I began to think coffee might be expensive for the purpose. I've noticed no ill-effects on my coffee (or the grinder) so far.  (The time I put chocolate chips in the grinder was a disaster, however... but that's a different story).
FWIW I detest the GW 25mm round bases, particularly for this use. It's not that they stand up too high, but that they are difficult to pick up, with the result that I tend to pick bases up by the fragile plastic figures. It's a problem shared by the beveled-edge FOW bases, nice as they are. Hence my liking for the double-thickness woodsie bases.
Litko aerosystems also makes purpose-built plywood bases that are, admittedly, higher quality and more regular than 'woodsies.'
Finally, I continue to be surprised by just how useful elmer's white glue can be in adhering most anything to wood.  Much better than cyano or plastic glue because you can brush it on, and your brush will llve to see another day.  And then there's the fact that a gallon of white glue sells for ~$10... as does a 'large' 2oz bottle of cyanoacrylate.
That said, I just sourced a bunch of cut stone disks (37mm diameter, and, I'm told, 25mm diameter).  I may start playing around with these as well.