I know you are probably looking for very cheap (or free) but if you can afford to spend £90 (or less) you can buy a nice Stronglight triple chainset from Spa Cycles and a Shimano UN55 from Chain Reaction Cycles. I did that when I put a triple on my Cannondale last year and it works beautifully. Looks good too!
I was allowing extra for the bottom bracket - the chainset itself was £75.I only paid £75.39 for my 105 Triple chainset from ribble last month.