I have used just about every extension you can think of, honestly.
I LOVE K2store. Of course, I am a fan of K2 and these two together are the one-two-punch knockout combo.
Do yourself a favor and try them both together!
Ramesh, the developer, is AWESOME, fast and friendly and genuinely cares about you and your project!
Thanks Ramesh! Thanks K2! Thanks Joomla!