Since you're looking to move towards DMX towards the end of the year, here are a couple of ideas to keep in mind:
(even for those of you just starting out)
DMX-capable fixtures, especially the ADJ ones, often have stand-alone modes. While the DMX fixtures may cost more, they often help you retain your investment as they integrate into a DMX environment.
WARNING: Check the DMX traits to ensure you are getting everything you want in DMX mode. Specifically, check for sound active mode in DMX mode, this is a popular issue.
Second item you want to look for is the "run all night" feature". This way you don't have to worry about duty cycles. This is becoming less and less of an issue, and is almost never an issue with LED fixtures.
Third: How are you planning to control things now? Since you're planning to go DMX, that's good. In the meantime, how are you planning to turn on and off the fixtures you're not using? Are you going to buy dimmer packs? That can start getting pricy. For less than the price of 2 good ADJ dimmers, you can get MyDMX. For less than 1 dimmer and 1 inexpensive DMX console, you can get MyDMX.
Not saying you can't plug a DMX fixture into a dimmer pack, which you can if you're running that fixture as a stand-alone fixture. But, this is excessive expenditures.
Ideally, MyDMX is so affordable, it makes sense to jump in with both feet. But, I'd add in the cost of a netbook to run MyDMX just for the convenience of it. I'm planning to purchase a netbook, which will be optimized for only running MyDMX. For sub-$350, it's not a big problem. I might spend a bit more and get a machine a bit more "disaster-recovery" friendly, you know, with an optical drive.