Hmm, 4k. Obviously must be spent on astro gear, there's no decision there.
As for what, well it would get a nice SBIG, but not nice enough. I think I'd go with these:
1) Megrez 80mm F/7 ED Triplet APO OTA, Package includes 2 speed Focuser, 2" Extender and Carrying Case $1440AUD
2) Vixen Sphinx SXW mount $2425AUD
Mmmmm. Never can resist good WO gear, and I'm dieing to own a Sphynx just for the fun of it.
OK, now I'm depressed that I don't have any money to buy new astro toys. Thanks.
Roger.