I personally would stay away from plantsalive, I've had some bad experiences with them, and so have others. Basically they are terrible quality plants, and the packaging means that everything is wrecked by time it reaches you anyway. Some poeple seem to have had success with plants alive though. For me it was a waste of money, all my plants from them died. While when I got the same species from a different supplier, they are still thriving.
I would recommend greenline if you want cheap plants, from what I've been reading they seem to offer great service, and they offer a wide variety of plants. I plan on using them in the future for some bits and bobs, but for the most part I don't buy cheap plants anymore and stick with tropica plants from aqua essentials, you pay for what you get.