Here are some options, from a mail-order dealer I've had good experiences with for a long time: http://www.micromark.com/vises.html .
I've been using a basic Panavise for about 35 years. I inherited it from my father, who got it as a Christmas present from an uncle longer ago than that. I've given it a coat of paint, and straightened out the handle once (it got bent when, in a moment of over-enthusiasm, I whacked it a little too hard with a hammer). Otherwise it looks like it did 35 years ago. The only real drawback to the Panavise, so far as I know, is the price. (If you do get one, I recommend getting a set of the soft jaws for it. I haven't found it necessary to fasten it to the workbench - but I've got another, slightly larger vise permanently mounted.)
The cheaper, similar-looking metal vise farther down the page looks to me like it would work fine for the vast majority of model building jobs. And I've ogled at the Dremel version in the shops several times; it looks like a good tool as well.
Hope that helps a little. You're right: a reasonably good vise is a huge asset to a modeler's workbench.
Good luck.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.