I used chalk paint on fabric but not vinyl; you might want to check to see if that is an option. You really don't have anything to lose.

I had some similar ones and I was able to buy the entire top piece as a replacement. That was quite a while ago though.

Buy new unless you adore them

agree with Jan, especially as somebody out there will adore these, unruined.

http://www.seatsandstools.com/replacements/

Thank you all.

One thing to consider is taking off the back of the chairs. Covering only the round seat would likely be an easier DIY project and/or less expensive pro project. Since there are three, consider trying just one and see how it turns out. You'd still have a matching pair to keep, sell, trade or give away.