Thanks

Very nice ,

... that's Keith signing a poster? although I do think I see a closed book to one side? ...

Still available

May I ask (i) which Phillips office (New York?) and (ii) which particular specialist at Phillips were comfortable judging this doodle, signature and date to be genuine?

Separately, do you have the $5,000 - $7,000 Phillips estimate in writing, along with any other comments the auction house may have made?

It seems a couple of unsigned copies of these museum catalogues (in good condition) recently sold for around £30 to £50. Regarding yours, everything rides on whether you're able to ease concerns potential buyers may have about the authenticity of the signed drawing. The YouTube video posted above is inconclusive; anyone in possession of a catalogue could use it after creating their own forgery.

Without credible and convincing accompanying documentation, like a clear letter from Phillips including its estimate, I believe your chances of securing a sale here for anywhere close to £2,600 are slim — especially given the volume of fake Keith Haring artwork currently in circulation.

Thank you for the prompt replies. Leibowitz is a colourful character and, I'm sure you know, an artist himself.

While it doesn't offer certainty (auction houses are very careful with the legal wording they use about authenticity in their Ts & Cs), the correspondence with Phillips does help to bolster confidence, corroborating the view that the signed drawing is genuine.

It sounds like you may at this point have dismissed the option, but in your position I would reconsider a consignment at auction, provided the low estimate offered was acceptable. With Haring being so sought-after, you may be able to argue for the work's inclusion in a prints and multiples sale, rather than a more niche (and lower-profile) rare books sale.

A sale at an established auction house will usually make buyers more comfortable about spending more, given the relative security and provenance they're getting. It requires some patience, but the net amount you would end up with (after seller's fees, etc.) may well be higher than what you'd otherwise receive. Private sales can often be a false economy — financially, in terms of the time and effort required, and also the hassles you sometimes need to put up with.

Lroy your messages and interventions are very exciting and informative, very constructive too.
Love your comments. Thanks.

Be careful with the compliments, Lroy. At some point in the future, I'll probably challenge your use of of the word "mint"! 

In French, it would be similar to, "En parfait état, impeccable, sans aucun défaut, sans aucune faille" — meaning this objective, extreme term is only justified in exceptional circumstances when referring to the condition of printed works on paper. Any attempt to relativise the word must, in my view, be quickly shot down.

Everybody is so nice to eachother on this forum! :-)