I generally purchase most of my mailing supplies at Staples. The prices are competitive and usually in stock. If not on stock they usually have free shipping as an option so I am well serviced.
I found the bubble wrap envelopes were too expensive compare to using two Kraft envelopes. It only takes a little more effort to double wrap a package with the lessor cost envelopes. No complaints from my customers.
Staples 9" x 12" Brown Kraft Clasp Envelopes are ideal for placing tax papers receipts or other info during tax time. They can be personalized by sticking an address label for your company on them. The best envelopes to use on a budget.
The envelope flap does not stay closed. The glue does not work properly so one must use the clasp and Scotch tape to have a secure closure of the envelope.
I use this envelope in large quantities I get them everywhere I love getting it from staples but sometimes there's batches that the clasp comes off easily