In what do you "wrap" your photographs for clients?

[arigram]

I have been giving people copies of photographs in the black envelopes that paper comes in. I really like them but since I am trying to turn professional, I would like to know in what material do you "wrap" the photographs to give to a customer/client. Can you buy those envelopes in quantities or is there some other material that could be used. Plain paper envelopes with a logo is an idea. Is there something more fancy?

[arigram]

Ok, does somebody know atleast if the black plastic bags that companies use to wrap their photo paper can be bought seperately? Are they special or any black plastic bag would do?

[blaze-on]

I just use the clearfile archival sleeves for the different sizes, and for larger print sizes, slip in a stiff thin piece of cardboard.