Last weekend I bit-the-bullet and bought a refrigerated air dryer from Harbor Freight. With a 30% discount coupon, the price was right. Works with compressors up to 21 CFM; maximum pressure is 140 CFM.

Harbor Freight also has a variety of air filters and compressor automatic drain kits.

A stated above, your pipe-plumbing can be done in a design that causes a lot of moisture to condense before it reaches your filters/tools/sprayers. (look-at and read both pages - good information here)