SKF's are the primo seals, IMO, but are about $35/leg. Never had a set fail.
Usual causes of failure are nicks or gouges in the fork tube (caused by rocks or debris hitting the tube) in the area of fork travel. Rough spot on tube rubs across seal until seal fails. Most minor nicks can be removed with 600-800 grit sandpaper (sand perpendicular, not in long direction of tube). Extreme cases - bent forks. Could just be a defective seal.
Fork servicing cost will vary - it'll be cheaper if you remove and reinstall forks yourself. Usually in the range of $150-200. For the cost of parts and a couple of tools, you can replace the seals yourself. The only specialty tools you need is a fork oil level gauge and the seal driver ($50-60 for both). Fork rebuilds on the R3 are about as easy as they come, you save some money and pick up a new skill.