Just remember that the difference between good kit and bad kit could save your life!
As Ziggy and Nat say, go for the best quality helmet you can afford. I used to have a second hand knackered old lid when I was younger, and on buying my first Arai it was like going from a Rover Metro to a Mercedes CLK! I've always bought them since (Arais, not a Metros) as they fit my head better than any others - my head wasn't the right shape for a Shoei.
You can get some real bargains by shopping around. If you're not worried about having this year's colours or styles, try going to one of the bigger places that advertise in MCN (like J&S or Padgets) as they usually have plenty of "last year's models" at great prices - same goes for leathers, boots and gloves too.
I'd also recommend Hein Gericke as they make quality leathers and are probably one of the cheapest on the market. Their tribal suits are a steal at 300 quid, and sometimes they do special offers on these. Check for your local dealer:
http://www.gericke.com/ Just don't be tempted to buy something because it's cheap. Make sure that you're buying proper motorcycle kit and not "fashion" biker jackets/trousers which are made from much thinner leather and without all the extra stitching on the seams. If you can, wait until one of the big bike shows - NEC in november, BMF rally (just gone) or the Alexandra Palace show - as you can pick up some really good cheap kit from these.