Where to find cardboards for sports cards shipping ?

[jaydee12321]

Hi,

I would like to ship my sold sports cards with a very thick piece of paper like that one on the photo below.  Tried to find some on eBay with no success.

Does somebody know where I can find such shipping material ? Thanks

[shoeboxgold]

We have lots of cardboard boxes, not suitable for reuse, that we cut to size and insert in padded envelopes. Cheap, and reuses cardbpard that would otherwise go in recycling.