Wideangle - Decision Taken or Did I?

I thought I had made the decision on my wide angle lens. I thought the wide angle lens tt will join my 28-135 in my kit wud be Sigma 10-20mm.
Decided to go for Sigma coz of
* Slight price adv (~50$)
* Extra 2mm

Now the next step was to get it from a local store.
I called around 20 stores today including
Wolf Camera, San Jose Camera, Ritz Camera, Kamera Korner, Keeble & Shuchat.
Only in one Wolf Camera, the camera was available. But it was 570$!

Now the options are
* Buy the lens for 570 whose actual cost is 480$
* Get it online - This is the last thing I want to do.

So again I am rethinking of Tokina.

Advantages of Tokina are
* Fixed focal length
* Almost 'L' Quality

Tokina vs Sigma


Current decision is.
If I get Tokina for <500 in any local store, I will buy it.
I have to call all stores again. Oh.. Not today!