The signature basses saved money sometimes.What I say is from my experience.Back in a day's i thought that make "custom" basses would get me to my sound nirvana but it did not.Just to explain what i mean by custom, buying picups from different brands, preamps, hardware,luthiers made to me basses with them and so on,you know what i mean by this.In the end they were good instruments after all but final sound goal to achieve is slipping away.Did it cost to me money all the time. Finally I decide to get signatured basses because i love the sound of the artist they represent.Now i am happy because i have three of them: Ibanez ANB205,Ibanez GWB 205 and Fender Roscoe Beck V so could cover any tonal range i wish for.Well the one i wish to have is fretless Jaco jazz bass but is too expensive but who knows maybe some day...
Behind the artist and their signatures stays professionals,money,time to experiments and knowledge so ut is hard to beat this when you try to get your sound,well most of the time.So, to me is easiest way to get sound that is in your head....and less expensive.