Startups are by the very nature of them cash strapped. I cannot speak for all startups but from my personal experience, we were forced to scrap together to buy the software we needed to start our business. For example, we were using trial versions of visual studio to build our prototype, and when it ran out were able to get a professional license as a door prize. And latter we upgraded to a single MSDN Team Suite DB Edition license.
I've also mumbled to myself that Microsoft should help early stage startups, it trully is in their best interest, since if our company succeddes, we will be buying lots of their products. The MSDN licenses can run anywhere from 2k-5k dollars.
It turns Microsoft has been addressing this need, by essentially giving away their best development tools. The Microsoft Bizspark program gives an unlimited number of MSDN Team Suite licenses for a cost of $100.00 (payable when you exit the program). There are many other benefits in the program, but this one was great. Pitty we can't return our earlier MSDN subscribtion, but this will save us thousands of dollars as we add more developers and grow over the next couple of years.
You can also read more about the program here: http://blogs.msdn.com/somasegar/archive/2008/11/05/bizspark-software-for-startups.aspx