Consider too what you want your vintage machine to do. I have a vintage dressmaker with a ton of ZZ stitches and a FW for piecing. There are a lot of variables depending on treadle, HC or Electric or ZZ. Obvs. if it's a ZZ, make sure all the stitches work (including reverse). I generally try out the machine if the hand wheel moves. I sew a minute or so, chat up the seller, sew some more, repeat until you're comfortable. Take a scrap of your own fabric that you would regularly sew on, make sure the bobbin winder works, check wiring and check for goodies. Remember, if you feel like you got a fair price and so does the seller and you are happy with your purchase then you got a good deal. Good luck!