Philosophers' Imprint Now Charging a "Submission Fee" of $20

MOVING TO FRONT FROM SEPTEMBER 12--SEE UPDATE

See here.  It seems quite understandable that revenue is needed, but I wonder what philosophers think of this model?  Given that PI has been quite successful and also quite selective, I imagine some philosophers will be deterred from submitting.  Might a smaller submission fee and then a higher publication fee upon acceptance work better?  Thoughts from readers?  Signed comments preferred.

UPDATE:   Professor Velleman comments below that they have decided to change the policy; he writes:

Thank you all for your comments. In response to the concerns expressed here, we have changed our proposed policy. Our submissions page now asks for a donation, with a suggested amount of $20.00. Authors can replace the suggested amount with any amount of $1.00 or more.

We are grateful for everyone's help in fashioning a workable model for funding.

I hope that those who submit to PI will donate proportional to their means, which may mean $1 for some, and more than $20 for others.  This strikes me, at least, as a very sensible and fair proposal, and it's now up to the philosophical community to make it work.