There is so much to consider that we need to narrow it down a little. What model Winchester are you looking at?
What is your budget?
How big are your deer and at what range will you be shooting?
The .44-40 will make a dandy shorter ranged deer round but you will have to reload them. The factory offerings are loaded very light so people don't blow up old black powder era Winchesters. 38-40s are also a nice bullet, my personal favorite.
You mentioned "good to fair" condition, in the world of antique winchesters, those terms indicate one in not so good shape as far as shooting goes. You would want one in verygood to excellant condition, that doesn't mean a pristine gun, just one that could be shot pretty well.
Take a look At Gunbroker.com and see what you find, the prices listed there can often be inflated but sometimes a reasonable one slips by.
1860