You just have to find a print shop that will print on vellum or buy some vellum sheets and print it yourself on a home photo inkjet printer.
That said, many consumer-grade (home) printers don't have presets for vellum (meaning the printer won't apply ink to the surface of the vellum correctly) so you're probably better off finding a print shop that will print on vellum if you don't have a very nice printer that can be set for printing on vellum.
|National Gallery of Art by Kukla|
from Your City - Black and White (in colour!)
|Hummingbird and Bee by dibilio57|
from My Best Photo of the Week
|The Snowy Egret by Lee8282|
from Color - Monochrome
|Skate Boarder dpr-0927 by vbuhay|
from Skateboarding Cover shot