Phil
This crowd have some pretty good products, I haven't done a garage floor with it just parking areas and driveway;
http://www.parchem.com.au
2 part sealer and tint will cost about $190 for 20lt. Some branches seem a bit dearer than others. I've found Riverstone pretty good and I think there's one in Penrith. Heed the safety warnings it can be nasty.
The product I used was this one, with a charcoal tint;
'The Coloured Concrete Sealer system is ideal for colouring and protecting plain concrete. It is a two part system; Part A the colour sealer clear base and Part B the colour tint. The Colour Tint (Part B) is added to the Colour Sealer Clear Base (Part A), and then applied using a roller or soft bristled broom'
They have other products as well, see the brochure.
cheers