what''''s the weekly cost of sails?
Cruising year in/year out, folks rarely sail their boats as frequently as you suggest. More often, they hippity-hop from one major Point A to the next major Point B with interim stops if they''re available, then spend an extended period in the new location as they did the old one (perhaps for the temperate season, or to avoid hurricane season, or for a refit, or...).
Beyond that, here are some reasons why it''s tough to answer your question:
1. Some of us are far more tolerant of older/tired sails, while others require more optimum sail shape and dedicate their kitty accordingly.
2. Some boats are less able to benefit from good sails (altho'' all boats do benefit significantly) and so older/more tired sails are viewed as more acceptable/less important.
3. Some crew tend their sails less when underway, leading to more chafe, abuse thru late reefing, etc.
4. "Cruising" means many different things to us. Offshore 24/7 sail use is vastly different than summering on the Chesapeake, even with a sail every day (which is atypical). Offshore use itself includes hugely differing conditions (transiting across the trades, variables, sleigh ride crossing the Atlantic, etc.)
4. Some rigs invite more problems than others, with more chafe points, fewer reefing options, fewer light air sails available, etc.
And these are just reasons why this is difficult to compute when assuming full-time use. For 95% of boat owners, it''s probably even tougher.