http://coins.about.com/od/coinvalue...e_values.htm says $1.00.
http://values.hobbizine.com/mercury-dimes.html says $3.80.
http://cointrackers.com/Mercury-Head-Dime.php says $5ish (no grade used).
And based on ungraded coins on e-bay, I see $3-$5ish for some coins that look like they could be VF.
But I'm no expert. Call a few coin shops, tell them what you've got, and they'll give you an idea of what they'd pay for it I'm sure.
Hope that helps.