If you don't want to get too elaborate (and you're on a budget), I suggest
beer and wine (a white zin is a good choice), vodka and gin (with tonic & 7-up
to mix), perhaps a blend (let's say Seagrams 7, with coke or 7-up mixers) and
then possibly margaritas (which you can mix ahead of time and just pour over
ice). This should cover just about everyone's alcoholic tastes. After all,
if you don't have exactly what they normally drink, they'll partake from what
is available.
A lot depends on the age group and the function....is this a party for
friends? Co-workers? Business? And the age group involved....if the purpose
is to get totally obliterated, then add jaeger, goldschlager and tequila for
shots.
Good luck!