Bought a new Ric 4003 in 2015 that set me back about $62,000.
$60,000 of that was a completely remodeled kitchen. She got a new kitchen and I got a new bass.
Therefore, for me, the bass is the most expensive part of my “rig”.
I usually say that my next bass will be my most expensive since it will probably come with a divorce.
Actually, my lovely wife and I have an agreement: she doesn't ask me how many basses I have, and I don't ask her how many mermaid tails she has. We both let our freak flag fly in different ways.
As to the biggest cost, it's the bass. Rics don't come cheap. My next expensive was just under a grand. Amps would be next at about $600.