Ignoring my bitsas (as the missus tries to....), my longest keeper bass was also my cheapest - I think I paid £200 around 20 years ago. Factory fretless Ovation Magnum 1. It probably wouldn't be seen as a budget bass now, but nobody wanted them then. I'm lucky enough to also own a Wal mk 1 custom fretless and Kramer 450B fretless, but if I had to go down to one - it would be the Ovation staying.