It's right at $500 retail, but I just got a used iBasso IT04 for less than I originally paid for the FLC 8S (in 2014), and to me it's a clear upgrade. Well, the FLC might have a more pleasant midrange, but the clarity, detail, and soundstage of the iBasso is excellent.
It may be a matter of taste, but I also think the Flares Pro 2 HD are superior. Amazing detail and soundstage depth. Again, at $529 MSRP, it's a bit higher than your stated budget, but IMO it would be worth keeping an eye out for a used set.
The FLC is still one of my favorite sets of all time, though.