Go to a violin shop, not a general purpose music store. Tell the sales person that you’re a beginner looking to learn fiddle. Try out a bunch of different fiddles, some in your price range, some a bit higher priced. Even if you can’t play yet, hold them and see how they feel in your hands. Bring a fiddle playing friend with you to help you evaluate the instruments if you possibly can. Get your fiddle playing friend, or the sales person, to play each of the instruments while you listen with your back turned, and choose the fiddle that sounds best to you. Personally, I greatly prefer used fiddles to new ones, the used ones have been "played in" and generally sound better than the shiny brand-new ones in the same price range.

In my experience, good fiddles come in natural wood colors ranging from a light golden to a dark chocolate brown. The fiddles you see on Ebay in green, purple, blue, silver, and so on, are generally cheap instruments covered with thick heavy finish. I wouldn’t buy one, certainly not without trying them out first to see what they sound like.

Don’t forget about the bow! Too often, beginners spend all their money on the fiddle and get a cheap bow, and then wonder why its so hard to play fiddle. If you have only a limited amount of money to spend, you’ll be better off and learn faster with a good bow and a cheap fiddle, rather than a good fiddle and a cheap bow. A good bow is properly balanced and weighted and responds well to do what you want; a cheap badly made bow makes you feel like you have to fight with it to get it to do what you want. Carbon fiber bows, like Coda brand, are relatively inexpensive but excellent quality for the price especially compared to wood bows of the same price.
References :
playing old-time fiddle for 18 years