+1 on the Dunlop flats. I tried them on a Sire P bass, they were amazing! Problem is I won't spend what they are now asking for them now days, more than what i paid for some of my basses! Back to the OP question, how about Embassy or a Guild Starfire?
The Embassy is definitely also an option, I can attest to its fat neck but I'm not entirely sold on the new blackguard look. Also I already own a Thunderbird with 760 Probuckers as my main roundwound bass! For regular (non-phat flatwound "workout") playing I actually like the relatively slim Thunderbird neck a lot.
Flatwound prices in China:
Most affordable are Alice and Höfner Contemporary, ¥100 or about $15. Both also come in relatively light gauges and sound like "halfway between round and flat" strings.
A bit higher is a local brand called Earthworm, ¥150 or about $22.5. They make very nice flatwounds but horrible roundwounds.
At ¥270 or about $40 is SIT Power Flats, GHS P Flats, and Rotosound RS77LD. Strangely the RS77LE costs almost double, and the dealer doesn't readily carry short-or medium-scale Rotos.
At about ¥360 or $55 is La Bella 760, Fender 9050, EB Cobalt and the like. Special La Bellas such as the Olinto or LTF cost a bit more.
Top of the line? Thomastik at ¥670 or $100. Fortunately I'm not particularly a fan of that tone (heresy, blasphemy, etc.)...