Genuine factory and genuine replacement plugs are the Denso ones above (FK20HR11). 6 of those shipped for under $100 is the best idea I've heard ...
Click here for service specifications (page 3), showing this plug as the only service part. The same part appears in the repair manual that is floating around in this forum (not the camrystuff.com one, but the site appears to be down for the past 3 weeks anyway).
That said, I know the Champion C57YC fits/runs and is only $18.55 each (6 for $111.30) excluding shipping from Victoria (that's just the first site I looked at). That engine was running an aftermarket ECU, so I can't say there wouldn't be any problems.
Thanks mate think i will stick with the genuine ones and do a bit of shopping.
Cheers
Peter