Where can I find this specific type of 8.5x11 paper?

The ampersand seems to be getting mangled in the post. Go to Red River Paper's http://www.redrivercatalog.com/ and select "Glossy Inkjet Papers" from the categories and select either the 38 lb. or 55 lb. Frio Gloss.

the paper that the kinko's person was talking about is C1S, coated 1 side. it's not really useful for what you're doing unless you're planning on getting an offset printer to print up more than 500 copies for you. the uncoated side is not matte coated, it's just simply uncoated. there is really nothing on the market that is matte coated on one side and gloss on the other that I'm aware of. one (expensive) option is to get a cast coated, or enameled cover weight (maybe a C2s, coated 2 side) stock, and then get a dull or matte varnish printed on one side, that's the only way that I can think of that you would be able to get exactly what you're looking for, and you're talking about a chunk of change. Regardless, you're not going to be able to get professional quality head shots off your home ink jet printer, no matter what the sales brochures tell you.

Southworth makes http://www.southworth.com/catalog/product_info.php?products_id=92&osCsid=26fd929c554a72569a7b88b2df4090b9 inkjet paper. I bought mine at OfficeDepoMax.

I'm thinking you only need a small batch, as you mention just this one audition... but I suppose you know about quantity headshot duping places like ABC? (http://www.futurecasting2000.com/resources.htm). http://www.ippaper.com/hammermill_home.html makes some nice heavy laser gloss papers. I have not run into any watermarks, and it feels a lot like RC photo paper. I've found I get better results by having it run on the color machine, in "black and white" mode, whatever that means.

yes, a small batch around 60-100 are needed. it's one audition in front of over 60 theatres so I need enough for every casting agent/director. thanks folks! C1S ahh!!! I definitely was not printing this at home but thought if I could find the paper and purchase it elsewhere the print job might be cheaper. i'm counting my cents so the eventual move to seattle (where said audition is) can come easier.

If your headshots are simply photographs printed on a high-gloss B&W stock, can't you just print via inkjet onto the backs? I do this with promotional pieces from time to time - i.e., inkjet-print postcard backs onto 5x7 photographs. Ilford makes some nice glossy stuff that's completely matte on the back.

You might try to find a printer who has an HP Indigo press. You get offset-quality prints that are affordable in short runs. Not cheap, but affordable. And C1S is a standard option. Turnaround time is pretty quick, too, since no plates are involved (The Indigo press is the mutant child of a laser printer and an offset press).