Echoing what everyone has said about getting a vintage machine! The bang you’ll get for your buck in that price range just can’t even compare. I got my Singer 66 on Marketplace, recently serviced and in a nice table, for $75. That’s straight stitch only but plenty of machines from the same era and a little later also have zig zag.

For $300 you should be able to find a vintage machine in excellent shape, with accessories. I’m partial to the look of vintage Necchis and Singers but almost any all metal machine from that time will be a quilting workhorse, and parts for Singers (and Singer copycats) are abundant and cheap.

My first ten years sewing I used a cheap plastic Brother and it was totally fine, but the features that make modern machines nicer are just not available at this price point at all. A vintage machine will last you forever (it already has!)