There are a couple of good deals going on right now from Best Buy and others that knock down $300 from the baseline 12" Retina Macbook. But with the rMB now 11 month-old and in dire need for a refresh, I recommend waiting. The new chips would have better graphics and CPU power that provide users more headroom for this computing needs. More at On Apple.
If you ask around, friends or go into forums, the common sense recommendation is that there is always something better around the corner and if you need to get a new Mac now or are faced with an adequate deal, pull the trigger. And if you can wait, wait. However, this is a unique situation here.
The 12" Macbook on the market is a first generation computer. And as with most first generation device, from Apple or anyone else, typically are really beta devices that customers pay for the privilege of owning and using. This was the same for the original Macbook Air and iPhone. This was also the same for the Xbox from Microsoft. The Galaxy S 2 from Samsung was a much improved device than the original Galaxy.
Furthermore, there were complaints about this Macbook regarding its compromises. One common complain is the lack of parts and only one USB-C port is available for expansion. If you find this a constraint and hope for a second port, might as wait a couple of months and hope that Apple adds a second port. However, I would not hold my breath. The design evolution from Apple is that we will eventually lose all ports and everything will be connected wirelessly. And this includes charging. Perhaps, that will not happen in the immediate future but it will happen.
So for now, hold tight. Wait. You will not regret it.