Hi. I recognise that car as i have spotted it a few times in North staffordshire. Yes it had the 296bhp engine at the time which was a 20 bhp increase on the original engine. They did 100 in Kuro and 76 in Ultra yellow. I own a yellow one (no 43). So basically the differences were the engine, wheels and anniversary badges on the wings plus you got a Playstation 2 console and a gt4 game.. Not sure on the value though i would like to think they do hold a bit more value, though in these difficult times its hard to tell.
A bit more info here.
http://www.350z-tech.com/zwiki/35th_Anniversary_350Z
Are you a local to Staffordshire?