Unfortunately, there's sort of a formula to this whole issue- I fly a LOT with my bass and have gone down just about every route there is. The equation goes "Value of bass- cost of case - size and weight = I should have been a dentist!"

Seriously though, there's a trade-off between cost & size/weight of protection to convenience or "checkability".
My preferred transport is carrying on a gig bag. This involves some planning ahead of time (knowing what airline, their "official" policies, type of aircraft, etc...) &
an extra large dose of people skills!!! I'd say that 85% of the time I manage to carry my bag on. Occasionally I'll have to gate-check it, but have never had any damage result. I use a hemp Levy's deluxe bag. LOTS of padding in it! (but still fits in virtually all overhead bins except commuter aircraft)
If I cannot carry-on, or feel like it's going to be too much of a hassle to try (certain airlines, holiday travel, etc...), I use the SKB Bass Safe. I've checked my bass in the gigbag, in the SKB over a hundred times at this point with no problems. Never paid any excess/oversize fees either. And this includes a number of overseas trips!
I have a collection of Anvil-style road cases that I
used to check, but the tightened airline purse strings post-9/11 have made this financially un-viable (as you discovered!).
There are some great threads on this subject, if you spend some time searching. You'll find opinions & experiences with different airlines as well as opinions on case products. I cannot emphasize enough, however, 2 very important points regarding air travel with your instrument:
1)
INSURANCE - There's
no excuse not to get it. 'All-risk" policies are available from a myriad of sources at extremely affordable rates. If you're rocking an F-Bass 6'er- this is a no brainer!
2) PEOPLE SKILLS - Your ability to work with airline employees to accomplish your end goal (safe bass delivery) is sooo important.
No case offers 100% protection against damage or theft. Sorry, it doesn't exist. The best you can do is to get someone "on your side" that day. All airline policies are flexible to those who successfully communicate & are fortunate to find a cooperative crew person. If you're in line to check in, wait for the friendliest (or at the minimum,
least surly) agent. Smile, and rummage up all of the friendly charisma you can muster! I've gotten my bass in the cabin more times than I can count by just being friendly!
My .02, but an experienced .02!
