What is the value of a 38 caliber Eastern Arms Revolver?

Eastern Arms was a Sears Roebuck trade name and the only reference I find listing a .38 revolver says they were made by Meriden Arms, which was a Sears subsidiary and in business only from c. 1905-1915. If your gun has grips marked Forhand Arms, I'd bet that the whole gun was made by that company and marked with the Sears name. That would agree with your estimate of the age as the Forehand name was used from 1890 to 1902. The only top-break .38 Revolver I find listed is the "Perfection Automatic" but my references disagree on the exact dates of production. The Standard Catalog of Firearms says 1898-1902 while The 1983 Official Price Guide says they were all made before 1899. The Standard Catalog suggests a value of $150 in NRA Very Good condition. I don't think the Eastern name would affect the value either way.