Optic for Trevox?

Just ordered a Umarex Trevox .177 pistol from ebay after seeing a review on GTA the other day.

Thinking a basic mini reflex red dot would work for me. In my search I ran across the Sig Air 3 moa

sight at Berrelli's, or whatever, for $49. 

Downers- No picatinny adapter included

Uppers- $49, Sig

I can spend more but was hoping to keep it under the $75,or whatever, delivered price for the this pistol.

So to make a short story longer, any opinions on SIG AIR red dots?