Have you ever noticed that good red wine vinegar actually costs a fair amount? I have. It costs me about $9Cdn for a decent half litre. My U-brew wine costs about $3 for that much so it's worth doing. All you need is 'mother'. Mother is the yeast that turns alcohol into vinegar. You probably can't buy it locally so you have to develop your own which is quite easy. Buy a bottle of unpasturized apple cider vinegar. It has live yeast culture.
Turn the bottle of cider upside down and let the particulate settle into the neck. Then holding it upside down open the top and let 1/4 to 1/2 cup of cider vinegar and particulate out into a bowl or wide mouth glass container like I have there. Add half a bottle of red wine to the cider vinegar. Cover with cheese cloth to keep flies out and put in a dark cupboard. In 4 to 6 weeks, give it a smell, it should smell like vinegar. Give it a taste to see how far along it is. When it's ready just bottle and use it as is. Use this first batch as the 'mother' for your next batch.
Mine still continued to work after I bottled it so a bit of gas popped out when I opened it. I make sure to open the bottle every day so the pressure doesn't build up and explode the bottle. I started with a wonderful tasting wine and the vinegar is better than anything I've tried from the store, at any price.