Back in 2003, Dave Roper, co-founder of Australian messenger-bag company Crumpler, accepted a case of Corona as payment from one of his cash-strapped customers. From July 17 through 21, the tradition continues with Crumpler’s Beer for Bags sale (45 Spring St., nr. Mulberry St.; 212-334-9391). Lagers listed on crumpler.com count as currency: Bring in a twelve-pack of Guinness and a bottle of Grady’s, for example, and get a camera bag valued at $65; two cases of Six Point buy a fifteen-inch laptop satchel worth $150. Shoppers will also receive two tickets to a secret party with live music and free helpings of the store’s liquid earnings.