Those pulleys are possibly one of the most difficult items of everything on the BOM. If you really want the 30 tooth, it’s probably worth waiting on it. However, if you can source a pulley with a different tooth count, all you have to do is change a setting in Ground Control.
You asked this question in your PM but I think others could benefit from the answer as well:
This is really easy, just requires a little math. The setting you need to change is for Z axis pitch. We need to change this value anyways to switch over the Meticulous Z-axis.
I’ve detailed the math in the Community Garden instructions page:
So, a 32 tooth pulley paired with a 10 tooth has a gear ratio of 3.2. We can plug that into the above formula:
Z = - ( 7.125 * 3.2 )
Z = - 22.8
And for a 40 tooth pulley, we have a gear ratio of 4.
Z = - ( 7.125 * 4 )
Z = - 28.5
I do want to make a quick disclaimer about the 40 tooth pulley. I don’t know of any machines that have used such an extreme gear ratio. Currently a 30 tooth is the recommended one and it seems to work pretty well. A 32 isn’t too much more, so it should be fine. Now, it’s entirely possible that the stock motor won’t care and work just fine with a 40 tooth, but I can’t guarantee that. If you want to test it, by all means, report back your findings either way. It would be greatly beneficial for all of us to know if it’s a possibility. I’ve been planning on testing it myself, but as I’m sure most people around here know, I haven’t had a lot of time for testing lately. 
Once you calculate the pitch, you need to confirm that the calculated pitch is correct for the actual machine. I detail the process of dialing that in the instructions:
Let me know if you have any questions, I’m here to help! 