I recently bought a Sigma 18-125mm F3.5-5.6 DC lens. It cost me just over ยฃ200 which is dirt cheap for a good range Zoom lens.
My initial reaction to the lens is favorable – though I have not used it much – it is a good zoom range and the optics seem to perform well. I did notice some barrel distortion and vignetting but this is to be expected on a low budget lens. The vignetting is easily fixed in the Photoshop RAW plugin.
I do not really have a good sample to post that was taken with the lens, the weather has been bad here for some time and I have been spending some time off work and off life in general being incredibly lazy at home.