Where to find boxes for safely shipping Vinyl LPs?


Are there cardboard boxes specifically made for safe and convenient shipping of just one or two LPs? Where can I buy them?

I have been trading LPs with friends and have found that it was hard to find the right box (thin, flat and strong) to ship just one or two LPs. I ended up using big boxes with lots of packing material, which raised the shipping cost unreasonably.

Any suggestions?

Sleeve City has cardboard LP mailers, and they have a pretty good reputation for the stuff they sell.
Some rave about using Pizza boxes.

Thanks guys for your help! The two sites have everything that I need and much more. Even the Pizza-box recommendation sounds interesting. I guess I should start eating a lot more pizzas--no anchovies, though, unless the album is a real stinker!
Your local pizza place will sell you new pizza boxes for cheap. I wouldn't dare use one that isn't new. Good luck and I'll have a deep dish, hold the anchovies.