Best is always better, but cacl2 soln for making competent cells does not really need best reagents. You are dealing with bugs, not molecules such as DNA, RNA.
You will get good results as long as you do the technique right. In my view the most important part of the technique, and the one that a lot of people get wrong, is using the bacteria grown to early log phase, and no more.
So. Now that you have your first ever question on bioforum answered (or not), mail yourself your username and password so you don't forget them, and then come back soon to update us on how it all worked out. That's how you build Karma in science.