We run a folk club, and we also perform (not as full-time professionals, but we do occasionally get paid).
The club doesn't have many paid, professional guests (maybe only 2 or 3 per year) - we run the club mainly as a platform where people can come along and do a floor spot or maybe an extended set and hone their performing skills. The club meets twice per month and what we take on the door and from the raffle goes towards maintaining the club (PA equipment, website, publicity, raffle prizes, etc) as well as building up a kitty to pay for guests. www.ashingtonfolkclub.co.uk
We don't haggle/negotiate with guests - if we book them, we pay them what they ask. Some ask for a flat fee, some a guarantee against a percentage of the door... either way is OK.
As performers we play many floor spots at as many venues as we can get to. If we are booked as guests we may ask for a flat fee (usually it will barely cover expenses for the gig), or we're equally happy to take a cut of the door money (last time we suggested 50% - with no guarantee - from a small local club, and the organiser insisted on 100%).
Jimmy & Val (jiva)