You have to realize a couple of things about luthiers:
1) these are guys who choose to spend the majority of their time in dusty shops fondling large esoteric chunks of wood in order to make a living. That's a little weird, no?
2) They are the only people on earth who really understand these large esoteric chunks of wood, because they have spent most of their lives learning how to make them behave. They have to understand not only woodworking, but also how it relates to nuances of sound and tone. What kind of a nutcase would choose this occupation? (Answer: only someone who really loves these large esoteric chunks of wood)
3) While they might be great craftsmen, they aren't psychic, and they aren't magicians - although if you're lucky, they might be
musicians, which helps. They can't know what the wood is going to do over x period of time, or what kind of temperature/humidity fluctuations the large chunks of antique wood will be subjected to, or what kind of physical abuse it will be taking.
4) Around here, the prices you quoted seem entirely normal. The closest major bass shop to my location quotes a price of $1500 just to remove the top and put it back, regardless of other repairs. When my old American Standard had a screw/button repair on the neck (which was nearly off the bass at the time) about 5 years ago, it cost about $400, and held until I sold it just recently with no problems. Sure it's a gamble, but how is a luthier to know what other weaknesses might exist in the wood around the cracks? I'd say if the luthier is reputable and thinks the repair will work, and you like the bass, go ahead and get it fixed before the damage from the tension gets worse. Just my .02c .
