Error 20 Dollar Note?

Hello!

I've ben looking for some time for some error bankotes, especially USDs, but since I'm far from being an expert, I'd like to ask what you guys think about this note. To me it seems like a “spilled ink” error, but I'm not sure. 

Maybe you guys know if it's worth the 23USD (+ 4USD) Shipping he's askig for

I'm afraid it could be like a marker or something. Idk. U know better. Thanks a bunch!

It is probably a bit of ink spillage - the ink is the right colour - but the ink spillage is so minor that it is difficult to justify a premium over face value on such a heavily circulated note. This type of error note is quite common among US error notes.

It could also be marker ink!

It could also be marker ink!

Yes, it looks like Post Production Damage (PPD) to me b/c the ink is too bright. 

Serial_Number_8

It could also be marker ink!

Yes, it looks like Post Production Damage (PPD) to me b/c the ink is too bright. 

I agree, someone spilled green ink on it, but not the BEP.