As a whole, shelf and mantel clocks aren't worth much money. Even if they are very old. I have a George Marsh mantel clock from the 1840's (not as pretty as yours) and I paid a whole $70 for it. And it sat on CL for about a year at that price. Granted mine needed a few parts but they still aren't worth much. After looking at similar New Haven clocks on ebay and other sites, I'd say yours is worth about $350 if it has all the parts, isn't damaged and runs perfectly. It's a huge deal if it doesn't run. Clock repair men are EXPENSIVE (usually $70 an hour with a 1 hour minimum) and clocks are nearly impossible to fix yourself.
There are several New Haven clocks from the 1800's on ebay right now. They are less elaborate than yours and some have starting bids in the $25.00 range with no bids. Sure, the fancy ones have asking prices that are very high. But that doesn't mean they actually sell for that much. It's kind of a hit and miss thing with clocks. Sometimes you're lucky and get a good amount of money for them. Sometimes you get $40. Gotta have the right buyer find it at the right time. People are very spoiled by technology these days. The idea of winding up an old clock all the time isn't very exciting when you can pop a battery into a new one and have it going for months. It becomes nothing more than a chore and a burden. Pretty sad, to me old clocks are amazing. They just aren't worth much monetarily unless they are something rare.