Err -- Is your wife also a wine newbie?
I would suggest rethinking this one. To get a good drinkable 20 year old wine will cost and even then -- as you are unused to the taste of old wines -- you are not likely to get any pleasure from it.
If you want to go ahead then I'd suggest getting a Port (called Porto in the USA). You should be able to get a 1992 Port for under $50 and it should be good drinking, but its for sipping as its a sweet fortified wine with an alcohol of around 20%. Thats waht keeps it drinkable after 20 years.
for some 1992 Ports available in US