All of them can be used (as they are equally good). I wouldn't use the check mark image. But the shopping basked, info bag and price tag are all good. If you pushed to choose just one, I'd choose the one with the price tag.
I like #1, the shopping cart with the i ... but personally I'd try a variation with BuyThe.info (capital B & T and introduce a .)
#5 (The last 1) is my favourite, super clean and the price tag/word merge makes it looks like a really professional logo!
Hi I think they are all really good! Although the tick box one is not that great, I much prefer the logo with the shopping cart and also the shopping tag one. They look professional too which will install confidence with potential customers!