Mech. in NY estimated $900+ for valve cover gasket replcmnt-North Carolina co$t?

What is your question?

Both sides Valve cover gasket leaks 1 drop@time but never have to add oil & gets 500mi/tank long-distance. Can't sit w/engine running in cold weather anymore due to stink & smoke. Will need to replace at some point soon - repairpal.com says under $400 in North Carolina? Why difference? Why does New York mechanic say he'll basically have to take engine apart to get to this gasket=high cost? Thanks.