No idea about a vendor. But SCARM and RR-Track both allow you to print out a plan in 1:1 actual size.
I'm pretty sure all of the original tubular track pieces would fit on an 8 1/2 x 11 sheet. So theoretically you could make your own patterns by using one of these software programs and printing your one-track "layouts" on cardstock in a home ink jet printer.
If you really need a larger sheet you might have to send the image files to a commercial printing service like Kinkos, Ridgeway, Office Depot or even some FedEx stores offer this service. Good luck!