Hi is a 1990’s Diamondback Assault 24 inch worth $200?

Is it clean, no flaking chrome, all original including the 3-piece cranks that day Diamondback on the arms, frame and everything 100% chromoly?
Are you the seller? Then yeah, maybe if you find someone who wants a cruiser size with classic geo and look.

Id check in the BMX forum here, and at BMX Museum though, to hear from those with specific experience. And look at your local listings for going rates for similar bikes, plus completed eBay listings for it.