My story....
I started with a 450D 18-55mm mk1 IS and a 55-250mm IS kit from Argos.
I added the 10-22mm EF-S USM (fantastic lens, money well spent - bought in New York from B and H).
I then added the 17-55mm EF-S F/2.8L IS USM used, (this was a good lens although started the dreaded lens creep when looking down) - and it started to get dust inside it. Takes absolutely fantastic photos on the 450D. (Traded in the 18-55mm IS for £50 too).
I then went mental sold the 55-250mm on eBay and bought the 70-200mm F/2.8L IS USM mk2 in San Diego whilst on business, best money I have ever spent on a lens. Was on at an instant $200 dollar rebate paid just a hair over £1500 new. (thanks overtime). This was my demise really, it produced such great quality images I was ruined and wanted more.
I then made the decision that I wanted a 7D so I picked up a refurbished 7D on eBay from Canon themselves for £750 with 12 months warranty. Sold the 450D on eBay. So at this point I owned the 7D, 10-22, 17-55mm, 70-200mm. I then splashed out on a 100mm macro IS USM F/2.8L courtesy of some Jessops vouchers for birthday e.t.c.
I was never really impressed with a the IQ/ISO of the 7D and I actually thought the 450D was better. So after a year of owning it I decided full frame was the way forwards. So the 17-55, 10-22 all got sold on eBay and the 16-35mmL mk2 arrived and 24-70mmL mk1 arrived for the 7D. Used this for a bit longer before eventually selling the 7D and buying the 5D mk3. I suppose I have been a FLICKR member since June 2009 so it all started just before that.
So my advice, buy the best body you can afford and slowly buy the lens afterwards, but whatever you do make sure you choose wisely and buy lenses you intend to keep. Try and figure out in advance where you are going with photography i.e. should I spend money and buy EF to start with as I would like a Full Frame eventually or I'll never buy that ever so EF-S is good enough.
I have taken some of my best photos with the 450D and the cheapo lenses, but there are certainly many more keepers now that I have better kit.