Bought 2nd hand from forums and realised 80mm was a tad big for my liking. Paid $60 for it so for sale at $60. Can post for about $5 i think. This is a pretty good gauge, deadly accurate.
EDIT: Forgot to add, it light's up at night too. Also has this funny dial thing with numbers that I've no idea what it does (see updated pic - if anyone knows what it does i'd love to know!). Oh yeah, it also has an adjustable bracket so all you need is double sided tape to mount it on the dash (i recommend sticky velcro!). Pretty much all you need to get going is vacuum hose (3mm internal, about $2 a metre) and a t-piece (if you need it, dunno how much but pretty cheap apparently). Both pretty cheap and easy to buy.