The only 1917s I've seen for under $300 have been basket cases: chopped, poorly refinished, rust buckets and etc. I think you are probably looking at a $500-600 gun. Any more and I'd keep looking. But they quit making them and the interest in them has been increasing steadily.
The bore on that one is rough but not uncommon for a 1917. It would make for a good shooter grade, something I wouldn't hesitate to use often and with great fun. But if you are looking for one in better shape, with nice shiny rifling and all, you better be prepared to shell out $800, or more. Either that or plan on being lucky. I'm with a couple of the others here in that I would be surprised if the seller would take less than $500 for that one, I wouldn't if it were mine.

John