£350 would be good for Neo, PS4 Slim might be about £250, or £220 to be really aggressive, not that they need to. I just can't see Neo releasing at a higher price than the PS4 originally did given the time that's passed and the limited amount of improvement it's bringing. Hell they might go crazy and bring it in under £350, as low as £300 would be a dream (Slim being £200 in that case).
Just ideas, no doubt I'll be wrong, but I was one of the ones who thought PS4 would hopefully be £350 while everyone was sure it would be £400 or more and I ended up being right then!