Do NOT buy the same spray that your local LE uses until you check your local laws regarding pepper spray. Laws vary state to state in regards to chemical sprays. Check your local laws first and then decide what to buy.
That said, I would recommend Aerko Freeze +P OC/CS.
If you can't find that, I would recommend a Sabre OC/CS spray.
If you can't use the OC/CS, I would recommend an OC/dye mix. If you have to use the spray, the dye can help LE identify the person you sprayed. If it is a visible dye, a person subjected to it may not want to stay around too long. I would shy away from the Kimber pepper blaster simply due to it's use of a pistol-type cartridge to propel the chemical - Too close to a firearm in function to risk carrying it around without a permit. Not worth getting in trouble just to have 2 blasts of pepper. A 2 oz can of spray can see more uses than just twice. I prefer a 4 oz can due to the size, easier to manipulate, and the can may be used for a defensive strike if need be.