The value of a vinegar cruet depends on what type it is and how old it is. The value for older cruets in excellent condition would be more valuable.
They're called "Cruets".
cruets
cruets
While you can use them for anything you would like to, in the majority of cases they are used to store vinegar, vinaigrettes or oil.
Cruets are the small containers that the wine and water are poured from into the chalice.
I think it is the category that salt, pepper, mustard, vinegar etc.. fall into. You can get 'cruet sets' that allow all of those substances to be decanted into decorative containers for use on the dining table.
Have a pair of oil and vinegar cruets and not sure how to make use of them? Not to worry - just about any recipe book or website with a section for salad dressings or bread dipping will feature several variations. For the basics, just look for a homemade Italian dressing recipe. Sites like AllRecipes are a good place to start.
The cruets are merely containers that hold the wine and water to me used at Mass. There is no significance to them other than being containers
Oil and vinegar sets can be constructed by starting with a basic olive oil and a red wine or balsamic vinegar. Dried whole herbs, such as thyme, rosemary and oregano are typically found in upscale oil and vinegar sets found at retailers.
The site Chef's Planet has a variety of glass cruets for sale. One could also check Amazon and E-Bay to get a good price and varied selection of choices. The store Crate and Barrel also has a lovely selection of pretty yet serviceable cruets.
Vintage glass cruets may be found on eBay, Replacements.com, TIAS.com, GoAntiques, poshchicago.com, Amazon.com, Ruby Lane, Etsy.com, ArtFire.com, eCrater and Bonanza.com.
made by Holt Howard pottery (Japan??) See current Ebay listing for Coq Rouge