The suggestions people have made are good. I have another thought.
Make sure and 'try out' the machine. I go to a craft day with some of my sister's friends (I think they ask me because a couple of them wanted to learn to quilt). One lady has a machine that clacks when it sews....like the machine is angry that it's having to do its job. I've oiled it for her but it still doesn't keep even stitches and it still clacks..... and moves around. You want a machine that sounds like it's happy to sew for you.... a nice hum or click, click, click like my featherweight. And you want it heavy enough that it stays put when you're sewing a couple of pieces together. There are many good machines out there but look for a good brand (no new Singer ... the newer ones aren't worth the price). I have 2 Vikings, 1 featherweight and 1 treadle. All but one were used when I found them. I had to buy a 1/4" foot and walking/ darning feet extra. I love them all, keep them clean and oiled and they love me.... sew like it's what they live for.
Good luck in your search. Let us know what you find.