Inexpensive Alternative to Canon EOS 18-55mm Kit Lens?

Hello,

I'm contemplating buying a Canon EOS T2i/550D or XSi/450D, however I went to look at the camera today in Best Buy and I'm not that impressed with the build quality/feel of the 18-55mm Kit Lens that comes with it.

If I buy the body only, can anybody recommend an inexpensive alternative that feels more solid/robust and still takes good pics? What about Sigma lenses? I found this one that looks pretty good...

Sigma AF 18-50mm f2.8-4.5 DC OS HSM Standard Zoom Digital Lens for Canon EOS:
http://www.canogacamera.com/detail.aspx?ID=48428

My main issue with the kit lens is that when you adjust the zoom it just feels really light and flimsy, there isn't much resistance. In comparison, when I looked at the Nikon D5000 with it's kit lens, it felt far more solid and robust and behaved the way I expected. I checked multiple cameras with the Canon kit lens, and all behaved the same way.