It's been a while!
I did end up buying some maternity clothes from Old Navy -- 2 pairs of jeans, 2 jumpsuits (I know it sounds weird, but they're jersey, very roomy, and insanely comfortable), a swimsuit, a pair of leggings and a pair of shorts. Maybe $150 all in, I don't remember. All are getting worn frequently, and nothing that I regret buying. I also bought a pair of silver Birkenstocks for about $90 on sale. They took a little time to break in, but I am so hooked. They're awesome, and I wear them with everything.
That was maybe 2 months ago, and nothing since then. I'm especially proud of myself for what I haven't bought and for breaking the "recreational browsing" habit which, inevitably, led to purchases. I had my eye on a very pretty dress that I tried to rationalize as "for a wedding" that's coming up in March. Which is very silly -- I have loads of dresses I could wear. The weird thing is, after a few pangs of desire, it kind of faded away. After a couple weeks, I stopped thinking about it and moved on.
I feel like this is the power of these kinds of challenges. Over time, you come to realize that you can make a change and, yes, it may feel like deprivation at first, but that feeling fades as your habits change. It gives you encouragement to get through the next tough change that will ultimately improve your life.