The only machine I regret on some level is a vintage Dressmaker machine I bought for $35 at an antique mall. It is super-cute but I did not realize at the time that it is a left-needle machine. I only make quilts, so I need a 1/4" seam but it is so hard to get with a left-needle machine. Oh well.... for $35 it can sit and look vintage.
I have been to shops and got so caught up in the demonstrations of the new machines that I nearly talked myself into getting one. But after thinking for an hour on it, I remember that I only piece quilts and have zero interest in making clothes or home decorating items or embroidery stuff. So I don't need anything they are pushing on the $5000 to $15,000 machines. I need something that will make a straight stitch and sometimes a zig-zag. Between my 1990's Bernina 1031 and my 1950's Singer 301 I am set for piecing. I do have a travel Janome machine inherited from my mother-in-law, and a Tiara II sit-down quilting machine. I thought I would regret the Tiara but it is one of the best purchases I have ever made.