If we would spend £20 each at a restaurant and we invite two friends over and spend £20 on food and £20 on wine, I count that as a win. Same cost to us but we usually have leftovers, we don't have to travel home late (as soon as it's over we can just roll into bed!), we invariably have a nicer and more relaxed time because there isn't some horrendous table next door screaming, and usually the guests reciprocate at some point, saving us the cost of a meal. Basically, if we break even I'm happy. The only thing that sucks is the washing up, but sometimes we just do really posh bread, meat, cheese and salad, so almost no washing up.