PSG are expected to push through a €222 million deal for the Brazil star despite La Liga attempting to block his departure from Barcelona.
And on Thursday he posted about the transfer on Twitter, with his kind words of praise coming with an apparent caveat.
"Congratulations to Nasser for the realization of this worldwide unique operation," he wrote.
"I'm impatient to know about the real costs of the operation."
Bravo à Nasser pour la réalisation d 7 opération unique dans le monde : Je suis très impatient de connaître le coût réel de l'opération ?— Jean-Michel AULAS (@JM_Aulas) August 2, 2017
Despite his reservations, Aulas later said Neymar's switch to the French capital would be an "immense" boost to the profile of Ligue 1.
Lyon finished fourth in France's top tier last term after ending the two previous seasons as runners-up to PSG.