If you can't do the work yourself, call around to several shops and get valve cover gasket replacement quotes. The gasket set itself is about $30 at Rock Auto.
Although labor cost for shops has risen steeply in the last several years, you can probably find some lower quotes for the job. Is it leaking enough to leave oil on your driveway ? Might just try cleaning the old grime off with some degreaser and a parts brush. The bolts aren't loose right ?