Ibanez!
Ibanez is one of the brands that gives you absolute best quality for the money they ask.
Even their cheapest budget line are mostly great instruments, bar the admittedly less great, but still fairly decent, hardware and electronics.
One of the SR, or even better one from their new headless EHB, series would be a good bet for a lightweight bass.
The cheapest model in the latter EHB series is almost exactly matching your budget limit, though being a bit of an acquired taste design wise, but the SR series giving you a wide array of different options at all sort of price points within you budget limit.
You could also consider a Danelectro Longhorn Bass, which actually both plays, sounds, and in my personal opinion also looks, genuinely awesome, despite being a fair deal under your budget limit (goes for just over 500$ from new), but it doesn't come much lighter than that.