Carl's is spot on with his comments, Andy Pruitt's book is a good read especially if you like Specialized, his approach is very much common sense based and emphasizes comfort. I would suggest it would be a sound investment even if you decide to pay for a professional fit.
I did some work with James from Specialized who teaches all of their BG fitters in the UK and watched him do a number of fits for the RYA who have a deal with them for their Olympic squad who do quite a lot of cycling as it's good low impact aerobic training (they are based at Weymouth so very good at hills, check out the contour lines). Interestingly, James fitted the Saxo bank team last year and most went Spesh's widest saddle.
From observations it isn't rocket science, we have done some fitting at work using motion analysis software designed for dynamic fitting (based on Pruitt's guidelines), which seem pretty good so there might be an opportunity for some free fitting if your prepared to be a guinea pig some time in the New Year, I will post a call for volunteers if needed.
However, what you often get from a shop fitting service is the opportunity to swap around components (mostly stems length angles etc., but also seat posts with various set-back), the BG system also looks at inserting shims in shoes to correct excessive knee movement etc., when necessary.
Often knee problems stem from the foot up so it is worth checking your cleats are properly set-up and perhaps switching to a pedal type which gives you more float, I moved to Speedplays because of knee problems and it seems to have done the trick, albeit at a price (£££).
Perhaps the basics of bike fitting could be included as one of the winter workshops proposed at the AGM.