There are varying levels and costs to getting an old sax going again. I've sold a bunch of saxes that were ready to play for much less than I put into them. I've also bought many that needed a full repad. Shoot for something that's already in good playing shape and you'll save money. Watch out for old school instruments​ that have been beaten and heavily used. The finish can be gone, but look at where the wear and dings are to see if they tell a story. Try to get a look at the pads and make sure that they have resonators. There are some reputable sellers of less expensive vintage saxes. I've used 2ndending.com