ASOS is originally an English online marketplace, I believe, but it’s selling in the US now. Their boast is that there’s free shipping both ways, and I will attest that they do honor that. Past orders have included a Panache Porcelain Plunge bra and a Freya Deco Strapless.
The selection seems to mostly be fashion collections with various random continuity stuff, so what you’ll get varies wildly. I’ve seen the Eveden and Panache collections, Miss Mandalay, Curvy Kate, Gossard, Lepel, and Wonderbra. The clearance section is a great place to snap up a find, and the regular inventory is cheaper than most places online. Something that burned me is that the bras are in US cup sizes: D, DD, F, G, H, I, J. I haven’t seen anything beyond M US. The British version of the site uses British sizing, but if you’re in the US the way to get the free shipping and returns is to use the US site. They might have different stock in the US versus UK.
Delivery takes about a week to Boston and comes in a reusable bag with a printed shipping label for returns, which is utterly and fantastically convenient. Since I don’t go with the majority of things I try on, that’s very valuable. However, you cannot do an exchange- only a return because of the way they seem to stock things. I’ve had to cancel an order before and it wasn’t difficult. However, I could not change just one item and had to cancel the whole order. My coupon code was apparently one-use and I found that I couldn’t use it on the new item.
All said, this is the most risk-free method of online shopping I’ve seen. The sizing can be confusing, and you may not find something you like, but if you do, give it a shot.