How much is "a small fortune"?
A few ideas.... (prices from
Camera Price Buster)
£99 ... Canon EF-S 18-55mm f3.5-5.6 IS
£159 ... Sigma 18-50mm f/2.8-4.5 DC OS HSM
£229 ... Canon EF-S 18-135mm f3.5-5.6 IS
£280 ... Canon EF-S 17-85mm f4-5.6 IS USM
£289 ... Sigma 18-200mm f/3.5-6.3 DC OS
£308 ... Sigma 17-70mm f/2.8-4 DC OS Macro HSM
£344 ... Tamron 17-50mm F/2.8 XR Di II VC
£360 ... Canon EF-S 18-200mm f3.5-5.6 IS
£499 ... Canon EF-S 15-85mm f3.5-5.6 IS USM
£520 ... Sigma 17-50mm f2.8 EX DC OS HSM
£675 ... Canon EF-S 17-55mm f2.8 IS USM
By and large, the more you pay, the better lens you'll get. The Canon 17-55 at the bottom of the list delivers superb image quality, but at a price. Personally I'm very impressed by the Canon 15-85, which I think is tons better than the Canon 17-85 I have on my 40D at present, but then so it should be at that price. If you want a super-zoom the Sigma 18-200 OS is good.
Trouble is, it's hard to look down the list and pick a lens that stands out as being significantly better value than the others around it.