I had to do quite a bit of searching to find a Model 10 locally. I live within the city limits of pretty big city, so all firearms are marked up here.
I paid WELL over $300 for mine, and it's a police turn-in (a model 10-6 with 4 inch heavy barrel). Came with some of the crappiest plastic grips I'd ever seen. I've probably put over 3000 rounds through it, and it just keep chugging along.
It was money well spent. If you're not sure you're going to like it, or if you're just looking for a .38 revolver, paying more than $300 might be a bad idea.
But as I say with all guns and cameras, if it's what you're sure you want, spend the money.
You'd have to offer me a once-in-life-time deal for me to sell or trade my Model 10 or my Nikon F3HP. And I probably "overpaid" for both.
**I'm a photojournalist by trade, if you could tell. Digital by day, film for what's important.