This might be useful for someone - spotted in this month's RSGB magazine. I'm not familiar with the different varieties, so apologies if they're not appropriate. Quoted verbatim from the small ads:

Surplus Philips P89C51RD+IA 64kB flash, 5gbp each. P89C664HFA 8gbp. Atmel P8258252-24pc and P82L58252-12pc at 8gbp each. All supplied with data and software (?? - my question marks!). G0MYX - robert.stephen@btinternet.com.

He's based Oxford/Swindon, UK. Don't respond to me - I'm only the messenger!

Dave