As one developer recently (and most astutely) noted, the current rate sheet states that setKeywordListMaxCpc and setKeywordListSingleMaxCpc operations consume 10 quota units each, while updateKeyword and updateKeywordList consume 1 quota unit each. Or as he puts it, "why would anybody use setKeywordListMaxCpc at a cost 10 per item when one can accomplish the same thing for only 2 per item using getKeywordList and updateKeywordList?"
Put simply, this was an oversight on our part that we will be correcting shortly.
Starting October 1, 2005, the updateKeyword and updateKeywordList operations will each consume 10 quota units per item.