My Kingdom for an Effective Strapless Bra

I had a very, very full weekend, one that found me out a lot and wearing a strapless bra every day (and interestingly, an airy, floaty dress that probably looked wretched on me). It was then that I realized how much I freaking abhor strapless bras, even this one that I bought duo's of last summer and that I thought would still work this year. Yeah, it kinda works, but it is not comfortable to wear for, say, three days of activity. And when I got up this morning and got out my Liberty of London halter-y (it is not actually a halter, just has a high neck and no shoulders...so it is a? I don't know. It is cute though, I'll tell you that) and realized I just couldn't do it with a regular bra, even though I am covering up with a cardi in office, I gave myself a momentary pity party. One more day of boob squishing. One more day of hiking this thing up every little bit. I resigned myself to it though, because it is hot, and the LoL top was the only thing I could think of putting myself into to any success. Then, I'm putting the bra on, thinking that I will set the convertible strap to halter (or to stun!), and the whole thing just breaks in my hands. Thanks, Victoria's Secret. Awesome. My $50 bra that I bought at the end of last year, EXPRESSLY for the purpose of having a convertible bra at the ready for early summer awesomeness was now in incapable of becoming a halter or anything else convertible. And the strapless-ness is not too great either because the little hook that broke has a remaining piece of metal that is stuck in its holder and keeps stabbing me. I ended up securing it with fashion tape and ignoring the pain. Wanting to be bra-strap free will make you do things like that.

So here's my question for you guys: what kind of strapless do you recommend? I would like to order one online because really, who knows when I'll actually make it to a mall to purchase one and be able to give this the time and care that such a delicate situation calls for. Plus, my options for bras are severely limited by living in the middle of nowhere (thus the fact that this other one came from VS which I really, really do not like). Any ideas? I really want something that is durable because this bra is going to take a licking from me, even if I buy a couple. And let's remember that I have humongo knockers to contend with.

Thank you in advance!