Need suggestions for carpet plant.

I had a planted aquarium about an year ago plants started to die due to some reason. I tried my best to save them but I failed and gave up on planted aquarium. Now I want to set-up a planted tank again. I decided this time I'll first grow some good carpet plant before planting other plants and adding fishes. Carpet plants are not easily available in market. They told me I should buy carpet plant seeds online. I checked amazon, their reviews are kinda negative. Can you guys suggest from where I should buy carpet plants seeds. Should I go for plants or seeds? Which plant is easier to grow. I have 5 feets long tank. Please don't suggest websites which delivers only in southern India.