I am with Denise P on this one. Lands End.
They do not sell maternity suits, but if you are not too big in the belly yet, you could probably use their suits. They sell one piece suits that you order your size in the suit, and your bra size. For example, you might order a size 4 or 6 with a DD or DDD bra. And if you got a tankini, you could easily use it through the summer. They sell tops that have all different kinds of options, from short to long torso (the long torso might be good for a maternity suit), underwires, no underwires, and they sell tops that go up to DDD. I know you said you are a G, but bear in mind that these Lands End suits run BIG. By their measurement chart, I needed a 14 DD suit. In clothing, I am usually a 12 or 14, and my bra size is 36 DD. I had to go down to a 12 C for a proper fit. So you could very well do fine with the DD or DDD top. These suits aren't cheap, but they're not super expensive either... and if you're desperate, I'm guessing you don't care that much. The other nice thing is that if you order the wrong size, you can return at a Sears store, and they don't charge you shipping on ordering a different size of the same item.
Good luck!
***EDITED***
YES, YES, YES, DEFINITELY CHECK THE OVERSTOCKS!!! There are GREAT discounts in there! Definitely check it out first.