Hi Oli,
First let me muddy the waters by explaining that I am a retailer and school owner.
There is partial truth in what has been told to you ..... partial! The gear you can buy 2nd hand should be priced at around 60% of the value of the new gear in the first year and will drop about a further 10% per year, each year after that. So 2nd hand gear can be quite cheap. Finding appropriate learning gear is another topic all together. Lots of high performance gear available as all the hotshots upgrade every year, and they're desperate to sell so many will tell you it is "great learner gear".
As for safety, the latest stuff is always evolving and getting better every year so the later the model, the more refined and tested the safety systems and flying characteristics. Having said that, most kites of 2007, 2008 and now 2009 are perfectly fine for learning and their safety systems are quite good and wind envelopes are quite broad. There are a couple which are more dodgy than others but thats not for me to say.
Everyone is biased to their own gear so you will never get an unbiased opinion, even from most average punters. Try and find someone you can trust and get a heading in the right direction and then go for it, if you take this advice you wont go too far wrong.
Good luck and welcome to the sport.
Good winds,

Watch out for
some of the budget/lesser known brands as their safety systems may not be as neat as the big name brands.