I "paid" a friend £50 to shoot my wedding. Which was a small affair in a registrars, just me and the Mrs, our 2 kids and her mum and my dad. He wanted to do it for free as a favour and £50 was the most he would take from me for his time. He took 40 or less shots, the thing lasted 30 mins and his PP time was about an hour. I just got him to put the end results on a memory stick.
The shots were practice for him, and better than me doing them myself. I would have paid him a couple of hundred but he insisted on £50 under duress.
When he did non mates weddings, he has a contract and also meets with the bride and groom beforehand to discuss what they want. He then charges based on total hours + shot requirement + PP time and if they want prints/albums or digital only etc. Cheapest wedding he did was £400 UK and some he charges maybe £1200-£1500 depending on the package. He likes his food so he usually negotiates a meal too
I think that my point is that he was worth more than £50, but we also had very low requirements for the shots and it was 30 mins shooting, 1 hour travel, I bought him a pint and he did 1 hour to do PP. But, for a "real" wedding he would spend a whole day, pay an assistant/second shooter, have meetings and emails to deal with, have to organise the wedding party, do an album presentation and spend a lot of time on PP.
What he got out of it was practice in a place he hadn't shot before ( he has had several shots there since ). An easy client requirement ( we both work at the same place and are friends, I just wanted some simple shots ) and a pint and £50 for 2.5 hours work, which is more than we earn at our main jobs.
I got some shots of our wedding and a nice guy who was a friend taking them.