I use flat marble papers from Vicki Shober co. and mount them to a sheet of PMA. Then you can cut your lenths to any width you like. One sheet, depending on the type of paper, can cost around 12.00 and will yeild practicly a life time supply at 1.00 @ ui for the service. very profitable and looks alot better than the tapes.
Oh, and I once learned the dead easy way to cut the mitres. At each corner, stack removable tape, leg of marble paper, removable tape again, other leg of marble paper. Cut miter with razor blade. carefully remove excess marble papers and removable tape. Perfect miter every time!
I actually still have several rolls of Mastermount tape left from Larson Juhl. Called them to find out pricing and it's been so long since they had it that they couldn't tell me the last price.
Actually had two botanicals I used tape with...came out nice, but even I was appalled at the price I charged based on the price marked on the box from "who knows when". The customer, an interior designer, was thrilled with the result and didn't flutter at the price. It was more expensive than the other botanical I did with a fillet.
Many decorative papers available from Graphic Products Corp. in Wheeling, IL. Phone 708-537-9300. Great family company owned by the Serafin's.