What’s a good alternative to rice wine vinegar?
Rice wine vinegar and rice vinegar are the same thing, so that's easy.
For additional pantry-stocking:
Seasoned rice vinegar is just rice vinegar with a little salt & sugar added. It's intended to be the right mixture for a number of recipes, not the least of which is sushi rice, although in my experience you're better off seasoning plain rice vinegar to the correct balance.
Rice wine is, of course, sake. Generally if you're cooking with rice wine you want a moderately priced, clear filtered sake like Gekkeikan. The same advice about cooking with regular wine applies here; don't try to cook with anything undrinkable.
Mirin is a specific kind of light, sweet rice wine used in braised dishes, dipping sauces, steamed fish, etc. If you can't find it, buy a drinkable sake and add around two teaspoons of sugar per 1/4 cup of sake.
Rice wine vinegar is not the same thing as rice vinegar. It is the difference between vinegar and white wine vinegar or red wine vinegar. I have been using rice wine vinegar for many, many years and do not know why you can no longer get it at the grocery store, as you once could. They sold both rice vinegar and rice wine vinegar and if you ever tasted them you would know there is a BIG difference.