I know we covered this somewhere, But I don't remember, How long is the event and is before,during or after dinner? This will help you judge. But generally I average 5 Hors de ouvers Per person per hour so for one hour you would need almost 375 pieces, But remember things like Crudites with seasanol veggies and dips and a simple brie en croute or lovely cheese display can acount for alot,Stationary items that are not individual portions can save you time and money. A chilled capanata served in hollowed out eggplant with Pita crisp is another example, and can be done ahead.Even a simple platter of exellent quility olives,artichokes maybe grilled and some bocconcini Or a large bowl of tomato and basil brushetta with some crostinis,most of these items are also cheap to produce, but serve up elegantly.I do relieze that Hdo production can be a bore, but think of things that the most time goes into the prep and the acual assemble of the Hdo is not as labor intensive. I hope this helps and makes a little sence