When I first started growing , I always went to an outdoor plant and tree nursery and bought used black plastic pots, they were the type that had ridges all the way around. I was paying 15 cents per 1 gallon plastic pot and 50 cent per 3 gallon, I never bought any 5 gallon plastic pots there but they had those too and charged $1.00 for those. They had 7 gallons also and those were $2.00. All the plastic used pots at outdoor plant nurseries will be filthy and caked up with crud, you'll have to wash them off inside and out with a hose and a soapy rag, but this is they way I would recommend if you want CHEAP pots.
2 gallon pots outside? Nah, I wouldn't even use 2 gallon pots inside. Like the others say, go 5 gallon for outside at the minimum. Every city and state normally has an outdoor plant nursery somewhere, everyone I've been to always sold used black plastic pots, and don't let them sell you the bad cracked ones. Buy 1 gallon and 5 gallon pots, transplant the 1's into the 5's.
Mine looked like these>
http://gthydroponics.com/images/NP300[1].jpg