Assume 15% of the invitees don't drink at all (or won't because they are designated drivers).
Assume 30% of the remaining drinkers don't like beer.
That leaves ~150 people who will "have some".
If you allow 2 bottles per homebrew "taster", that's 300 bottles or 6 batches.
Now...if you advertise 4 or 5 different styles of beer, you simply won't have enough because people will taste one style, and move on to another and before you know it, one person has trashed 5 bottles of beer.
One style only on the other hand...with six ounce serving cups, will stretch your bounty much further.
Still...I'd keg.
