Where to buy a Decent Leather Watch Strap for Under $12?

I bought a $2 leather watch strap from eBay but I want something more decent. The $2 one is actually alright but it's really thin and makes the watch look quite cheap and tacky. It also narrows in the middle and I think I'd prefer one that doesn't.

I'm hoping for something under $12 (including postage) that's maybe 3mm thick or more. Can be online or in a store. Is this possible? Or if not how much do I need to pay? I want a 20 mm wide black one.