Selling my 250 - How much value did it loose after spilling it

Most, if not all, of those for sale have been dropped at 1 time or another. Usually the damage isn't too bad.
My bikes were all dropped or crashed by POs, & only once the '85 was crashed by me.😳 You wouldn't know that I did that at 55mph now, it's all been fixed. If reasonable & good repairs have been done, they don't loose too much value.

I agree with Emil - these are Rebel 250 bikes, the long-time "starter bike". The 2002 I bought has been dropped, but the bike is in sound mechanical condition and there is little damage visible (very similar to what you described).
If I were buying a 20-year-old bike, with a reputation as a "learner bike", I wouldn't be surprised if it were dropped.
Based on your description, I wouldn't expect the new owner to replace those parts even if you lowered the cost by that amount.