1993 Volvo 940 Question: estimate to fix wet gskets, wet engine oil pan and oil cooler seepage

"wet gaskets" and "seepage" are signs that a gasket is starting to leak, but it can be like this for quite a long time before it actually starts leaking. Have you seen oil dripping on the ground? I would get a second opinion, I think this shop is over selling you on these jobs, but I haven't seen it to know for sure.
It's important that the PCV system is clear and not plugged up, this will cause oil to leak from many places.

Check oil constantly; like before each drive, until this is truly identified. RED FLAGS from original shop's alleged "insights." A bit of weeping is tiny in comparison to what it could be. I would not, however, reccomend that you blow this off. If there were a way to save headaches & wallets being harmed; it's for certain, hands down: PREVENTative maintenance. Yours is a Rear wheel drive, (RWD), so look in those (RWD) sections of websites. With patience it will be easy to find referrals to a real shop that has earned a reputation for honesty from Volvo OWNERS. See specific websites like Swedespeed, Turbobricks, IPDUSA; and look at their links, too. There is a huge following for these cars; in fact I am in dire need of BUYING a 940, 740 or 760 wagon myself; central IN. or central TX; (765) 401-4872; or DadSONvolvoProjectAThotmaildawtcawm

I do not think that this is as serious a problem as they are making it out to be. If you are losing lost of oil I would be worried, but If you are just getting an occasional drip, no big deal. I had similar seepage and simply checked the torque on the bolts and the leak stopped.