The size 9 1/2 shoes have the rainbow version of Apple’s logo stitched into the tongue and the side, and were made only for the company’s own staff, according to seller Heritage Auctions. Although bidding will begin at $15,000, Heritage is estimating the value of the lot at $30,000 or more.

Proxy bidding will open before the auction, and end 10 minutes prior, at 10:50 a.m. Central time (11:50 a.m. Eastern). Notably Heritage is imposing a “buyer’s premium” on successful bids, starting at 25 percent for the first $250,000.

Through partnerships, Apple offered a range of branded clothing and other non-electronic accessories for fans during the ’80s and ’90s. These included shirts, caps, bags, umbrellas, and even a sailboard.

The company has since scaled back dramatically, mostly limiting accessories to things like cables, cases, and headphones. One exception is “Designed by Apple in California,” a coffee table book with 450 photos of Macs, iPhones, iPods, and other products. It comes in two sizes, priced at $199 and $299, respectively.