[Furface]

Depends what you mean by coaching!
Most members at most clubs will give advice - ranging from excellent to positively dangerous - and most archers will eventually sift out the bits they like. Sometimes, an individual member will work with another on a specific bit of technique, but, when that is over, move on. Some people think of either of those as coaching; that happens at most clubs, and can be beneficial. It is certainly a very good way to move from Beginner to Improver. But this is really training rather than coaching
Coaching with a Coach is different, though. Both Archer and Coach are committed to working together for a long period, with the intention of helping the Archer reach her goals. They plan together - technique sessions, tournaments, diaries, fitness etc etc - and work together, sometimes quite intensely. In other words, it is a close working partnership to which both parties are committed. Of course, the goals might be anything from International archery to being able to group at 40 yards. When archers write of the benefits of working with a coach, this is probably what they mean. And it is terrifically rewarding for both sides.
As for cost, many coaches working at a club will do it for the love of it. However, there may be times when it is polite to offer expenses ("Come with me to my first tournament"). It may be that paying for coaching will become more common, as the emphasis on finance turns to development. And it would alter the balance of the relationship.
So first have some idea of what your goals might be; then approach a couple of coaches to see who suits you and your aims best. Then go for it