As with any antique, condition plays a critical role as does rarity and demand. If you have a trunk that's in good condition, is hard to find, and is in a style that a lot of people are looking for, then its value will be higher.
On the other hand, just because it's old doesn't mean it's worth a lot of money. Of course, that depends on what you consider a lot of money.
If your trunk has been in the family for years and your desire is to keep it in the family, then its value is sentimental and a monetary price can't really be placed on it. However, you will probably want to know its value for insurance purposes.
The values listed below are my opinion based on my experiences in buying and selling antique trunks. Others may have different opinions based on their experiences. Including a few antique trunk dealers that have many years of experience and knowledge in this field. Some of them can be found in the "Other Site Link" section of my web site.
Additionally, Paul Pat Morse and Linda Edelstein of "The Trunk Shop" have written an Antique Trunk identification and price guide that has a lot of valuable information. It can be purchased from their web site.
Original condition trunks generally don't sell as quickly as refinished trunks but they are much harder to find. A nice original condition trunk will generally be more valuable than a similar one that has been refinished.
Any trunk that has the original key that works the lock is very desirable to a potential buyer and should add $10 - $25 to that overall value.
If a trunk has been repainted its value is diminished because it's difficult to remove the old paint. Unless it's a rare style trunk or really well done, painted trunks are generally worth no more than $75 - $100.
Trunks in poor condition, with missing hardware, torn or missing covering, and cracks in the wood, are worth much less that the prices mentioned below.
Most trunks are solid wood covered with metal, leather, paper, or cloth. If the covering is coming off then the best value can generally be gained by stripping the material off and refinishing the trunk. The exception would be a metal covered trunk because of the difficulty in removing the metal.
Trunk re-finishers look for trunks with solid wood under the original covering. Some trunks have leather stretched over metal bands and some have leather or cloth over a fiber board material that resembles todays heavy cardboard. There isn't much that can be done with these trunks.
All of the stained wood trunks in my "Trunk Showcase" were originally covered with one of the materials listed above.
I'm listing antique trunk values by antique trunk style below. You can follow the link for each antique trunk style to find a brief description of each trunk and a sample picture of that style trunk. I've listed price ranges as a general guide. A range can give you an idea or a starting point but if you want to know the true value of any antique trunk it will need to be appraised by a certified appraiser or someone that has extensive knowledge of antique trunks.
Flat Top Trunks: As is condition $35 - $100; Original or refinished condition values can range from $150 - $400, with rarer trunks, like wall trunks, bringing the higher prices.
Dome Top Trunks: As-is condition $150 -$400. Original and refinished condition values can range from $300 - $1,200. The high end values are for Saratoga or Brides style trunks with ornate hardware and trays.
Half or Hat Trunks: As-is condition $150 - $250. Original and refinished condition values can range from $275 - $600.
Jenny Lind Trunks: As-is condition $150 - $300. Original and refinished condition values can range from $300 - $1,000.
Doll Trunks: As-is condition $35 - $275. Original and refinished condition values can range from $200 - $1,000. The high end values are for rarer style trunks like Jenny Lind and Oak Slat trunks.