I was going to look into sports bras. I still try to get to spin a couple of times a week as well as body balance (which is getting increasingly amusing as I seem to fall over sitting down, but hey)
izchaz - you are right about the wire being fine if it fits. but as you are experiencing, when you are pregnant that "perfect" fit will only be for about ten minutes.
You are constantly changing shape and will only know what has changed when it reaches a point, such as incredible discomfort, which might be too late
I also wanted to avoid the great expense and have been using freecycle and ebay to get maternity clothes and baby things. but a good bra is a good bra and I couldn't get away with any cheaper alternatives.
I do get a little peeved that maternity stuff costs so much more, even in sales. It is like they know they have you over a barrel.
But just so you know, when you go back to normal after your pregnancy, keep checking the figleaves and bravissimo websites. My preferred is figleaves where I have been able to buy proper boulder holders, that look nice, support well and show some cleavage for as little as £15. -for a bra, that is good in my opinion.
Also, once you have an account, it will keep on file what you have bought in the past, including size. So if you liked a particular bra and want to replace it or get more, all the information is just there, waiting for you.
One last thing that sells it for me is that the bras have real honest reviews from real honest people. So it helps to decide which bras to buy.
BTW - I don't work for them, although it might sound like it. but I hate bra shopping almost as much as jeans shopping and this makes the whole process easy and painless, plus you get post that isn't a bill!