Well, I can be the counter counter!
We are a pub cover band, but regardless to that we do get asked to play peoples weddings. we are not a function band and not 'professional' in the function band sense, but we are professional in the 'turn up and play what people want' way. We have played a fair few weddings, 2 in the last couple of months, we charge a fraction of what others charge, so more the £200 each than the £400 each you are talking about, but people have always seemed happy and we have had nice messages after the weddings.
The common thing in all the weddings is that we have been specifically asked by people who have seen us, so there is no surprise, we aren't advertising ourselves as a wedding band but if people want us, we are happy to do it, and they know what they are going to get.