I don't think there is any 'average' price as wedding cakes must surely vary from a few Kiplings to a monuMental (uneaten) J-Lo/Ben Affleck affair.
We got Konditor and Cook
http://www.konditorandcook.com/
to do our wedding cake(s), they were crazy individual fondant fancies, and I think they cost us about �300, for a wedding of 100 guests.....shoit thinking about it, we was had! Seriously, they were fab.
It's worth checking out their website.
Have fun.
I think this this cake designers prices would be hard to beat.
They range fron �150 for any two tier to �275 for any four tier.
Not many out there to top that?
Her website is http://www.cakesbyann.co.uk
Far too much !!! I'm getting a couple of Celebration (i.e. plain white iced) cakes from Tesco and decorating them with silk flowers to match my bouquet.