What a great old buggy! The market for these - as you can imagine - is rather thin and selective. Generally, through message boards and craigslist similar antique buggies in good condition sell at the $1,500 to $3,500 level (which would be a fine fair market value) but if you're looking for retail replacement value (insurance purposes) the cost is likely a reproduction cost - how much would it cost to make another one - which would be $5,000 to $6,500. Here's a great reference that shares a bit about the firm behind the buggy: http://www.coachbuilt.com/bui/h/hercules/hercules.htm
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