I ordered a Moving Comfort "Melbourne" XS from Sierra Trading Post (on sale for $15 + ship). I think the size chart is correct that it fits 30ABC-32B. I wear a CK 30D and the Moving Comfort fits alright except I'm squeezing out a bit at the armholes. Potential chafing spot but no discomfort as is. (I'm 4'10", 94 lb, 26 under-bust, 31 full, if that matters at all.) The material for this particular bra is thin though, so I wouldn't wear it on its own. No padding. I'm just glad I found something that fits snugly and doesn't cost a whole lot.

I second Lulu Lemon! A lot of places have decent customer service too if you explain your situation (I tell them I'm extremely small around the rib cage and still need a bit of support) and they have some great yoga tops that are good for hot yoga that fits pretty well. Expensive, but definitely worth the trip. I have bought their 0 and size 2 and have been very satisfied.

Shock Absorber starts at 28D or 30A, and as far as I can tell the bands range from tight to very tight. I've ordered the Level 3 Classic in 28D, but I tried on one of the Level 4 (highest support) models in 30C and it was definitely small enough... this did make it very difficult to pull on over my head and shoulders, so I chose the Level 3, which has a standard non-racerback fastening.

ETA: the 28D Shock Absorber is indeed tiny - it measures 19.5" unstretched and will barely stretch past 25-26". I haven't worn it out running yet, but it feels comfortable and very firm. Available at Figleaves, if anyone's interested.

Ahhh, just the thread I'm looking for!

I just got a Nike dri-fit reversible sports bra today in XS that ran AMAZINGLY small and is actually tight around my 25" ribcage. Since I don't have big boobs anyway (28B/30A), I don't quite care how the sports bra flattens me. BUT, I do mind how it's not padded at all, so the diamond cutters are all out there for the world to see. This kind of awkward since I like to run outdoors in my sports bra when it's warm enough.

So does anyone know any sports bras that would fit my ribcage and come with padding? I clicked on some of the links in the previous posts here, but they all say page unavailable because they were from a year or two ago.