Earlier quoted context omitted.
The New Yorker[1] has one of many references on the internet, but the price was 100,000 shares of pre-IPO Apple stock at $10 per share. The visit happened (over the protests of some at PARC). There are some side comments about the visit in "Triumph of the Nerds“. 1) http://www.newyorker.com/reporting/2011/05/16/110516fa_fact_...
Well then, you were entirely correct. I suppose that my search was both fairly cursory and didn't include all of the right search terms. I find it very surprising that this is the first I've heard of it, though; the "apple stole from xerox" meme is really entrenched, to the point that I never really doubted its truth.
Arguably we're fortunate that he struck this deal and brought these ideas into production much more effectively than Xerox was doing.