Vinyl Envelopes Reclosable Business Packaging - Where Do I Find Plastic String-close Envelopes?

Business packaging - where do I find plastic string-close envelopes? - vinyl envelopes reclosable

I like to use plastic / vinyl-8 1 / 2 x 11 envelopes that close with a string (like an envelope between the offices) for my business. I've seen, but now I can not find it. I tried Staples, Wal-Mart, Google, eBay - no luck. Anyone have any ideas?