I can't tell you exactly what he'll charge for your specific project, but personally, I was having bottle openers cut out of titanium sheet that was .125" thick.
It came out to about $3 to $4 per piece for me, but I was getting 100+ pieces at a time.
Price does/will depend on a few things:
Number of pieces - more pieces typically work out for less $ per piece.
type and thickness of material
how fine of a cut/finish is needed
complexity of design, i.e., how long will it take to cut each piece.
I'd give Mark a call and see what he says. He can probalby give you a rough idea of price, especially if you send him a CAD file or example of your design.
Another positive is that they just upgraded their waterjet at the end of last year. 5 axis head and tremendous accuracy. Pretty much eliminates taper that you sometimes get with other WJ machines, as I understand it.