OK, if your planning on buying them really cheap, go to any seafood store or grocery like I said, they are so much cheaper than the ones you would buy live. If theres a certain store that says everything is fresh, buy from there. I bought from a grocery store that claimed everything was fresh, and it was true! all clams turned out alive.
As for reviving them, you should get a cup and place each in, or a bucket or whatever, just make sure you aren't piling them on top of eachother. Then fill the cup or whatever with the main tank water, and wait 10-30 minutes, and even after, there are some that could be revived after an hour. But don't get frustrated if some do not open, those are the dead ones that you should throw out.
As they are revived by saltwater, you will be able to tell that they are alive because they will gradually open up and you will see their little hairs and parts. But the real sign is their "spitting". After they are revived, they release waste into the cup which I assume they have been storing in their shells when they were brought out of the water. Thats why you want them in cups and not in your main tank. After they start spitting, they will continue for 10-20 minutes, then you can put them in the tank.
Their care is pretty simple. They should have a deep sand bed to burrow in with their tongue, and good water flow to feed. And that should be it.
Any more questions, just ask. And good luck. And when your shopping for them, you want to look for the ones packed with ice or have been kept cold, not dried ones, or old ones on shelves. The ones with ice are generally alive.
