Found these on ebay for $140 w/shipping. I ran a search but didn't really find what I was looking for. how upgradable are these in terms of drop in replacement parts? I'm talking neck and pickups, if needed. My idea is to have a playable bass right away that I can upgrade over time. I had thought about building a warmoth, but the sx is non plywood alder so that could save me some money I'm thinking.