The value of ANY firearm is based on exact make, model, condition, and originality. Without those things, your question is rather like "What is a Ford automobile worth?". If you have an original Sharps, the value could be anywhere from $100 to several thousand dollars. It will need a "hands-on" appraisal for an accurate answer.
Sharps
Christian Sharps.
10-10000 USD depending on specifics
Sharps Rifle Manufacturing Company was created on 1851-10-09.
A few hundred to multiple thousands of USD depending on EXACTLY what you have.
2100 in fair condition. 4750 in excellent condition. That is for the carbine. The longer rifle....add 2000 to 5000 for excellent.
No one answer, since there was no one Sharps Rifle. Some were single shot and used metalic cartridges, some used paper or cloth cartridges.
Impossible to answer without the caliber.
Buffalo
check at: Antique Arms.Com
100-5000 usd
Sharps Rifle was a popular Union Rifle during the civil war