Here are examples of 10 types of whites and 10 reds that one can obtain
for $20 or less retail. A variety of choices, a few geeky but many
chosen for familiarity (important in restaurants- geeks are few and far
between). Trying to walk the tightrope between blandness and financial
suicide. I starred 4 of each to choose for by the glass.

What is available in NY is not the same as in Delaware, so I didn't
list specific producers. Your friend should go to a good wine shop and
price what is available there.

White
2 Chardonnays: 1 French (Macon or Chablis), 1 US*
1 Gruner Veltliner*
2 Pinot Gris: 1 Italian P. Grigio (not Santa Margherita) ,1 Oregon
2 Sauvignon Blancs: 1 NZ*, 1 Loire
1 Southern Italian : Falaghina or Greco di Tufo
2 Rieslings: 1 dry (Austrian, Alsace, or Australian), 1 off-dry German
(Kabinett level)*

Red
3 Cabernet Sauvignon based wines: 2 CA (*1 by glass), 1 Medoc Bordeaux
2 Merlot based wines: 1 CA, 1 Libournaise Bdx
2 Pinot Noirs: 1 Oregon*, 1 Burgundy*- a base Bourgogne or Cote
Chalonaise is fine
1 Barbera
1 Chianti or Cotes du Rhone*
1 more off-beat red (by US restaurant standards): maybe a Zwiegelt or
Loire cab franc

Then the reserve list, of which you would not need to stock much.
Retail could range from $25 to well over $100 for the mature Bordeaux,
Burgundy, Barolo.

Reserve List
White: One Smaragd or similar Gruner Veltliner, one upper end Alsace or
Austrian Riesling, 1 top German Spatlese Riesling, 2 white Burgundies,
1 demi-sec Vouvray, 1 expensive CA Chardonnay, plus a couple of geek
specials (maybe a mature Savennieres and

Red: Couple mature Bordeaux, couple Nebbiolo ( maybe one pricey mature
Barolo or Barbaresco and one from a forward vintage like 1997 or 2000),
couple Burgundies ( again maybe one mature from a good vintage and one
from a more recent forward vintage), one upper end OR PN, one similar
CA PN, two Rhones, 1 Amarone, 1 Brunello, 1 blockbuster Shiraz, 2 CA
Cabs (one mature), plus a couple of geek specials ( say a Taurasi and a
mature Loire Cab Franc).

Dessert wines (half-bottles or 500ml best):
3 or 4 :German, Sauternes ,Tokaji, US, Loire. Maybe one less expensive
(Monbazillac, Loupiac, Beaumes dVenise, etc) by glass.