Zoom Pentax 2.8 PRO to buy

[Qbert]

Hello,
I'm looking for high performance zoom for my Pentax *ist DL.

My first choice is:
Pentax 70-200 f2.8, but I think it's quite diffidult to find.

Other choices are:

Sigma APO
70-200 (or 210?)
100-300
135-400

Tamron 70-210 LD

Tokina
80-200
80-400

Thx
Qbert

[Qbert]

Sorry, Pentax is:

80-200 ED 2.8