Help me?

I have a Canon 1000d with 18-55mm kit and i have been doing some panos.
The lens i have for interior (bedrooms, wc, etc) is not so good, in fact I can't do any pano in perfect conditions.

I do not want to spend much money for a lens fot now, sigma 10-20mm or Tamron SP AF 10-24mm are good lens? Can eny one suggest another or some that does not go very far from どィ 500, 550どィ at most fisheye included.