I don't know of any reliable on-line sources to look up SN's on Winchesters made after 1963. If it is AE and drilled for scope mounts it is much newer than 1970's.
United States Repeating Arms Company (USRAC) bought the Winchester name in the late 70's and started making rifles on or about 1980. Look on the butt-plate or else where on the rifle and look for USRAC logo.
Quality, and value of the 94's has been all over the place since WW-2. Some of the late 60's and 1970's guns were pretty bad. USRAC made an effort to improve quality and generally 1980's and 1990's guns are pretty good.
Value seems all over the place too. I wouldn't pay $400 for a 1970's gun, but maybe $300. If it is a newer USRAC rifle you did good.