VERY easy repair! There isn't much interfering with getting the valve covers off in an E-Series of that vintage. Should be able to access all of it from inside with the doghouse off. Maybe one or two fasteners from under the hood. Gaskets are cheap so get the good ones. Clean the gasket surfaces well and flatten any dimples that have formed under the heads of the attaching capscrews. Install with a good sealer like Permatex Ultra Black. Spend a morning or afternoon plus about $30 and you're there. Shop? Don't know, probably $50 parts and 2-3 Hours labor so if labor's $100/Hour say $200-350.
No thanks, I'll get dirty.