To determine the value of a vintage trumpet, first inspect the trumpet to determine its condition and to look for any identifying markers. Depending on the make of the trumpet, the trumpet is more valuable if it is from a desirable company. Research similar trumpets through collectible books, guides and magazines, as well as through auction sites. If your search fails to yield results, consider taking the trumpet to an appraiser.
To find an estimated value through an auction site such as eBay, look at recent completed sales. Search for a comparable trumpet in similar condition, and check the final price on the auctions available. Alternately, call or visit an antique shop and ask the proprietor for an evaluation or whether the shop has a similar trumpet in stock.
Many times, the condition of the trumpet influences its estimated value. The best option for determining the condition is to have it graded by a professional who deals in antique instruments. A professional grade typically renders a high valuation and also prevents disputes with any potential buyers.
If all else fails, seek out an appraiser who specializes in vintage instruments. An appraiser is knowledgeable about current values and knows different instrument manufacturers. Many appraisers also know potential buyers and markets where your trumpet is desirable, if you want to sell.