JAileen, Bijou, and Thistle, you've posed some very good questions that need to be considered before making a decision. I have to balance frugality with pragmatism. I am learning that when I love something on sight, I should probably buy it if I can afford it, as so many items on offer just don't strike my fancy or aren't quite right for whatever reason.
Thistle, your question about the frequency of wears is sobering, though. I could see myself wearing this dress twice a month (at the most) for 6 months of the year, so maybe 12 wears per year. I tend to keep clothing for years -- until they are worn out or clearly dated. I imagine I would keep a dress like this for at least 5 years (maybe more). So, maybe 60 wears, for a full-price CPW (I'm including the cost of the belt) of approximately $3.25. I'm not really a number cruncher, but I think that's a number I could live with.
Christina, good point about making sure quality items get their proper wear. I am guilty of keeping nice items from frequent rotation just to keep them nice longer.
Cardiff girl and Kathie, thanks for the reminders that early sale prices do exist (usually before stock is depleted). And KMM, THANK YOU for that coupon code! A 20% discount would bring the CPW for the dress and belt down to $2.60. La Pedestrienne, thanks for confirming that it also includes free shipping.
Joyce, I have the advantage of owning the Marisa dress, which is a very similar cut, so I think I'd stick with the same size.