I assume you refer to personally funded trips?

I would happily spend one months salary on a single airfare ticket from savings and often do. But more relevant to my circumstances is how much % of your salary would you spend on a bookings for your whole family? This usually exceeds a months salary for at least one family trip per year. We normally have a few family trips where we use miles or MFU but we also have one trip where we pay for full CW fares (sale fares usually) and that has to come from my pocket.