And just to defend myself... ;)
When I see two brand new users on a forum (this is a forum btw, not a blog -- if you don't know the difference, you might want to learn it in your biz!), who register and post immediately to an ongoing thread (and not starting a new thread), and that's the only post they make, and they make it supporting/pushing a given product otherwise unrelated to the forum thread (that is, a 'simple cart plugin for wordpress'), I usually question the validity of those posts/accounts. That's not paranoia, that's experience. ;)
Also, given how 'green' most users are, I find I pick up on such small details more than others -- and given the level of fly-by-night and phishing operations out there, I try to point out things to more novice users. Yep, every once in a blue moon I'm wrong, and they are really separate people.
Even so, the fact a new-to-the-forum person shows up and posts about a commercial, and hosted, product that isn't related to WP, in a WP forum thread asking for a simple plugin for WP, would have sent up a red flag in my head, and should send it up in others. But, then adding to that, it's pretty bad when a SECOND new person comes into, 10 days after the last post to a thread and 'reiterates' the first new person's tangential "advice", RIGHT AFTER the OP (that's 'original poster' for non-forum folks) stated clearly that wasn't what was wanted:
I prefer to use those which is a WP plugins and yes, there are some plugins for it that is free so I won't resort to using paid ones.
I don't care if they are/were different people or not. Bad form to repeat an answer, after the thread has 'gone dry', that the OP made quite obvious wasn't desired.
BACK ON TOPIC: Thanks to Nnyan for jumping in productively and adding names and links to some of the WP plugins that the OP might actually be looking for!
There are obviously some pretty cool plugins around, would be interested to hear back from Truth (and stop, including myself!, the OT banter) as to what of those match/don't match and why. Others would be interested in both the 'evaluation' and even the developers need to hear feedback. ;)