I have analysed my GAS over the last 15 years, and realised that there is no 'ultimate bass' for me that does it all.
I like variety in tone and appearance, so have now got 3 main basses that should give me absolutely anything I need or want (Precision / Jazz / Stingray).
Since getting part 3 of the above, the GAS has died down, but still find myself looking for something to GAS for - the thrill of the hunt etc. Despite the fact anything additional will very likely replicate something I already have.