G'Day Frandy, from memory the gauges (which are autometer sport comp not the HSV ones as I wanted black to match my dash cluster) were about $100 each from American Autos, the binnicle I got from holden $140 (bit exy) and I bought the HSV adapter for the oil pressure sender unit to fit to the oil pump which was $75 I think, wired it all up myself and was a piece of piss to do, took about 3 hours all up. The head unit I had installed by Audiocom in Kal along with the plastic surround and replaced the speakers with pioneer splits in the front and pioneer 2 ways in the rear doors for $1300 all up which I consider good as that head unit was $1800 when first released. Make sure that your installer uses a plug that fits your original loom and wires the new head unit to that, so if you ever have to your old head unit fits back in with minimal problems. Stereo sounds alot better than the original head unit (especially with the 10 inch sub in the back!)
Enjoy