Where did you get the watch for $100, as a matter of interest? Looks really fantastic, especially with that strap!
They can be had for $149 on eBay & Amazon. I am very tempted!
Tissot has plenty of goodies well under a grand, Raymond Weil too, though I find the latter's designs are often very derivative of Cartier, and a friend who's bought a couple recently has had reliability issues. The first place I would look for new in this range is Baume & Mercier. They have designs like the Hampton that have been distinctively theirs for decades, and are always around on massive discounts on Jomashop and the like. I think the brand has a certain old fashioned romance about it too. If you can give or take a couple of hundred, or wait for the right deal of the week, there are quite a few options. I'd hold out for the Hampton if she likes the shape, otherwise the Lineas are always cheap.
Used, the world is your shellfish. My suggestion would be a simple Omega, easy to find at that price. Maybe there just aren't as many lady watch nerds, but smaller watches are just so much cheaper. Under a thousand you can find a solid gold ladies' watch, with an original presentation box (papers not so often), from a brand like Omega that's now got some real cachet. You might see the odd LeCoultre, Girard Perregaux or even Cartier if quartz is OK. But I'm thinking a gold, hand-wound classic Omega, perhaps from her birth year or some other date of meaning. There are a lot around.
I got my two at Ashford. Very pleased. When I pick my watch for the day I am always drawn to my "JR's" Ashford is always having sales, I got both of mine for $749 (each), flash sale. You won't be disappointed.
Warning: Spoiler! (Click to show)
Niiice. I don't need a second Terrascope but I have to admit that I sure do want one.
I am really drawn to this one. Waiting for a "flash sale"