If you're keen to build your own, then you're probably better off to get a 'kit' from a supplier - they usually contain the mirror blank, tool, gauge, grinding & polishing materials, instructions etc. You can get a kit from:
http://www.telescopes-astronomy.com....ccessories.htm
They also sell finished mirrors etc. Even if you don't want to build, you can get a good idea of the component prices.
Then compare that with ready built scopes (say a 8" or 10" or 12" dob) at your Melbourne Bintel for example, and you'll have an idea of where you want to go? A dob of those sizes will easily give you great views of Moon & planets etc. I've only got a 6" newt & I have no problems seeing stuff - the larger apertures are better for faint fuzzies & deep space, you don't need a large scope to start with (that comes later hahaha!)
But don't get one on eBay whatever you do. Unless you REALLY know your stuff you can get seriously burned 'coz there is just soooo much cr@p being flogged on eBay. Stick with reputable forums like this one, or reputable astro dealers.
Cheers, Fred...
PS. If you want a list of specific contacts for different materials etc. then PM me, I've been trawling the net for ages for my own research, so I can save you some time.