I have my number one (a Yamaha 5-string I got for a bargain price) which is genuinely the only one I need. I have a really nice jazz type thing that I use for drop-D stuff, a Harley Benton 5-string fretless and a Stagg EUB.
Everything else (about a dozen or so) are unusual or have an interesting story. They all sound quite different and it's good to have them available if I want to create a specific sound, alternatively they are just pretty things to hang on the wall and are generally not expensive. I think the most I've paid is £400.