I'm not fully understanding this... wasn't Culpepper #11?
When Culpepper was drafted, he was given #12. Before his second season, he changed his number to #11 which he had for the rest of his career with the Vikings. This jersey is rare. You can find replicas with #12 but it's hard to find the authentic/stitched ones. There's another guy who's selling one like mine on eBay and he's starting his auction at $150. His is the only other one I've ever seen like mine.