Nice image. It's in overall good condition, with a complete case and intact spine. The clasp looks to be a (relatively modern) replacement. The 1/9th plate size is common, and the facts that neither the subject nor the photographer are identified tend to suppress the value. The image itself is competently executed but not striking. I'd give it a range of $20-$50 depending on where you sell it and who happens to come along and bid on it, but most likely in the lower end of that range. If you go looking on eBay you'll see all kinds of prices out there on such things, but do a search on completed auctions to get a better idea of value. There's a lot of cased images listed there with enthusiastically inflated prices that keep showing up unsold, week after week.