Plugs, Valve and Pan Gaskets (Questions)

[The Judge <dismiss@earthlink.net>]

Gents:

I figured today was the day to replace the spark plugs (105k miles). 
While inspecting the plugs, I noticed there is oil residue on the block
near one of the plugs.  Is this a leak in the valve cover gasket?  If
so, how much to replace (I will not do it myself, have neither the time
nor the inclination right now)?

The last time I had the oil changed, I was told there is a small leak in
the oil pan gasket.  How much should this be to replace (i.e. have it
done)?

TIA, as always.

Todd
a/k/a
The Judge
'90 80Q (Leaking Oil)
'86 16v Scirocco (Wolfsburg Ed.)
'85 5KCS (Not Leaking Oil