About ten years ago I started doing more and more mounts. I tried a number of materials but have settled on cork bark as my favorite. It is easy to work with, never breaks down and has a pleasing textured surface.
This morning I took one of the large pieces I have and broke it up in to usable sizes. I broke the pieces off rather than sawing because I think it makes for a better look. I added the wire hooks and hung them up on a frame so I can choose from them next time I have a plant to mount. They are the seven pieces on the left side of the picture.

Early on I started looking for alternate sources of cork bark. At a retail price of $5-$10 for a small piece, I could see that the budget for plants was being eaten up by the cost of the bark. This was not a good long-term solution now that I needed more and more cork bark for mounting.
I looked for more information about cork bark on the Internet. I figured there must be someone selling it in larger amounts for a more reasonable price. I was thinking 20 pounds would be about right.
The only quantities I could find was in pallets, about 10 times as much as I wanted. I don't remember the price, but it seemed like a real bargain. I bought a pallet and I bet I never have to buy cork bark again.
Last but not least is the mailing box test. I could potentially sell or trade the mounted orchid and I hate to go searching for boxes that fit the plant while I am trying to pack for shipping. I have found out the hard way that it is much easier to adjust the cork before there is a plant, so I slip each one into a box I keep handy for just such testing.
My favorite shipping box is the USPS Priority Mail shoebox and I keep a stock of them handy. They are a great size for many plants, they are free, and the USPS delivers them right to my house. Check out USPS.gov for a great source of other shipping supplies.