And I know EXACTLY what you are talking about. I was 34G at 165lbs, now I'm more like a 34F/32G (and of course the smaller band sizes are even harder to find) and I usually have to oder bras from the UK. My last bra I actually found in a specialty European lingerie shop in Denver and it was... $100 :/. But they ARE good quality. I got one for around $55 last time... and the strap broke on me after less than a year.
But alas, I get some financial help for my clothing and luckily my mother is obsessed with good clothes and underwear. But she's completly right about the underwear. I refused for years to try on a bigger cup/smaller band size because I was in denial that I had big breasts (I recovered from an eating disorder and gained a lot of weight and with that came the boobs that I never knew existed) and didn't want her to spend a bunch of money on something I didn't feel I needed. But, wearing something that fits correctly feels makes a difference and is way, way more comfortable. Don't sacrifice too much comfort by going for bigger band size at a regular store if you really need something like a 32DDD!
I, too, wonder where we'll end up ultimately. How tall are you? The last time I was 125 lbs I was around a 34C/32D (and now that I know more about fitting and European sizing I wonder if I actually needed a 30E), but I was also 16 at the time so who knows. And with some muscle, I'd rather be at least 130 lbs to be honest. More curves and hotness I've decided . But yeah, not buying $100 bras would be nice!