Depends on your group of friends really. For us, yes, that would be far too much now, but before having DCs/before getting married, DH went a few stag dos overseas (often because he used to live overseas and so has friends living all over Europe, just getting the group of lads together for a few beers would involve international travel for half the group anyway!), I think a few cost in that region, but it was no big deal, they could all afford it easily and it was just an excuse for a boys trip away.
Now, we are living off DH's wage, we have much bigger living expenses and we couldn't afford it.
If the rest of hte group could easily afford that sort of trip, why not just because one or two couldn't, unless those people were considered "critical" (brother, BIL, best man etc).
My hen do was about £100 per head. DH's stag do, I've no idea, it was during the Rugby World cup in Paris, they went to an England game and stayed 2 nights in Paris, Eurostar over for the UK travellers (the European based ones made their own way, I think a few drove), it probably was very expensive, but at the time, all could easily afford it, I think the booking an afternoon off work to travel was the hardest part. Now, the same group of men pretty much all have mortgages and DCs so many probably wouldn't be able to do it.