I think when you're buying gear, one of the most important starting points is getting yourself kitted out so you can stay warm on the river. From that point of view, a decent cag would be a good bet. It's worth spending a bit of cash on getting a good cag. Make sure you treat it well and it will last for quite a long time.
If you stay warm while out paddling, the cold water and cold weather doesn't sap your strength. Same for booties. Get a decent pair of booties, or neoprene socks and river shoes if that's your preference. Make sure you stay warm on the river, then start looking at bigger things like helmet, BA, blades and boat.
There'll probably be heaps of people who disagree with me on this next point, but I think spending heaps of money on a 'bling' fashionable helmet (sweet helmets etc) that doesn't actually give full coverage over your ears is a waste of money. There's no protection on those sort of helmets if you bash the side of your head/face. Get a decent, comfortable helmet that covers your head properly. It'll be a lot cheaper than some of the trendier brands and will do just as good or better a job. If you want to bling it up, slap stickers and paint on it. It bugs me to see people who have bought themselves really expensive trendy helmets and paid so much for them that they couldn't afford extra thermals, booties, BA etc.
With the strength of the Euro against sterling at the moment, buy all of your gear online from the UK. It will work out a lot cheaper for you, even with shipping included.
