If the trunk belonged to one of your relatives then we can put no value on it. Keep it no matter what, DO NOT sell it. We can tell you countless stories of the folks who have dragged their sorry behinds into the shop, red eyes, begging for Grandad's trunk back. We tell them we're sorry, but the trunk was sold to a guy in Minnesota who stores his cross-dressing supplies in it when he isn't using it as a stand for his piranha tank. Trust us on this one, you'll be sorry you sold it.
Next, if it says 'Louis Vuitton' on it anywhere (or if it has little LV initials on everything from the tacks to the ribbons) you need to switch to more expensive scotch than the brand you've been swilling. Your trunk is worth a few thousand dollars, up to as much as $50,000. You may want to consider having a reputable antiques expert near you perform an appraisal to get a handle on what that thing is worth.
Third, if your trunk has been painted by someone (or, even worse, if you painted it yourself) it is extremely difficult to get more than about $100 to $150 out of it. Keep this in mind if you have a trunk that you're considering painting. Sit down, think on this for a good, long spell before you slap the pea-green paint to the old unit.
Dome tops sell at higher prices than flat tops. This has something to do with the fact that the same pricing relationship existed back in the days when everyone bought trunks - dome tops (camel backs, hump backs, whatever you call the darned things in your neck of the woods) were more expensive, by about 50 cents, than flat tops.
The average canvas-covered, flat-topped trunk in 'as-found' condition (most of the canvas is there, handles are broken, tray inside, smells like mothballs, has someone's name on the ends, some rust here and there) is worth about $100 to $200 un-refinished. Once you refinish it the value can range from $250 up to a high end of about $750. Little details determine where in that range the price will fall. If you paint anything on the trunk black or gold (metal banding, corners, etc) the trunk's value will fall in the low end of the range. Having the original key pushes the value up, as do any types of tags or labels indicating who made the trunk.
Remember - these are general guidelines, every trunk is different.
As of May 25, 2011:
We no longer offer a trunk appraisal service. Our appraisal reports took time to assemble and nobody ever seemed to be able to give us more than about 12 minutes to cough it up. To avoid pitching those poor souls into the gloomy pit of despair that apparently captured their very souls when we took more than 48 hours to complete their reports we just flat out dropped this service. You may want to speak with some antique dealers in your area to inquire about an appraisal. Also, it may be worth your while to spend some time looking at the closed listings on eBay. Use their 'Advanced Search' page, click the box that says 'Closed Listings' and use search terms that are relevant to your trunk. You might be able to find a similar trunk or two and you'll see what the final sale price was.