Marbled Geckoes are common as dirt over the whole region, it's a bit of a strange species to be looking for, you should have found bucket loads of them. Lacies are pretty widespread, but I don't know of anywhere they're especially common in western Victoria. You can find them pretty much anywhere there's a bit of half decent habitat, but it's just hit and miss finding one.
Stumpies are locally very common in some areas out that way, I've seen a few Jackies in western Victoria but not that many. I've seen more Beardies than Jackies around the Grampians. I've never seen a Red-bellied out that way and would quite like to. I've actually seen very few Red-bellieds in Victoria which actually sort of bothers me! For whatever reason, I seem much more prone to crossing paths with Tigers. Browns are of course very common through most of Victoria, especially out your way, anywhere away from water.
Pretty cool area you live in. I spent a lot of time in my teens and 20s camping around the Grampians, and a few other areas in that general area. I have a relative with a turkey farm in Dadswells Bridge, you might know of it, I've stayed out there many times. He says he gets Red-bellieds on the farm but unfortunately I've never seen one there.