Your best chance of getting it is contacting the current registrant and negotiating to buy it. After that, your best chance is buying it in auction or finding it listed with a “buy it now” price at a marketplace. Your other option is to find a broker who can negotiate on your behalf (if the domain name sells for a few thousand or higher…brokers likely won’t have the time or inclination to negotiate smaller deals).
By using GoDaddy auctions section, you can also use keywords to search the domain names that you are interested in. For instance, if you type the keyword something like “fitness”, it will list you out all the domain names that matches with the keyword “Fitness” so you can easily make a list of all the domain names with your desired keyword selection.
Premium Domain names are domains that are already registered, but are available for sale at a higher price. Sometimes it will be an individual selling the domain, or it could be the domain registry (Like Donuts Inc. or Radix) selling their top quality inventory at a higher price point. These domains can be priced anywhere from a couple extra bucks to millions, depending on the domain name, the level of interest, or the amount of traffic it organically receives.