WonderingWoman: The Serial number prefix BHE was used in March 1991, the prefix BHJ in July 1991, so your guns date of manufacture should fall between those two dates. Some of the three letter codes were manufactured out of date sequence, but it's a fair bet that your gun dates to that period.
The model 10-10 is the 10th engineering change to the model 10, which was the model number given in 1957 to the .38 Military & Police revolver. The .38 military & Police was the evolution through many engineering changes and two world wars of the .38 special Army & Navy Revolver introduced in 1899.
It is a fixed sight blued or nickeled steel revolver with a swing out cylinder built on the medium K frame. Caliber was .38 special, except for a small number chambered for and marked as .357 Magnum. The 10-10 was introduced in 1988.
The model 10 in all it's variations was probably the most common police service revolver in the world and only lost favor when semiautomatic pistols became more common. The model 10 is still in production today.
As to value, the Standard catalog of S&W gave a value of $365 for as new in box & $275 for excellent (used) condition in 2006. Prices seem to have shifted a lot since then so I suggest you check out sites such as www.gunbroker.com www.auctionarms.com
to find out more current pricing. If you sell it to a dealer you will not get a retail price, they will discount the amount they pay you so they can sell it for a profit.