I'd definitely see what you can get your hands on at the stores. I know PetSmart usually has tanks of plants..not too much. They are hit or miss on the quality. I've been going for awhile and they had some decent java ferns last time for cheap. They are having a sale here in the US til the end of the month I know on tetras and some plants and you could get some nice deals.
You can always buy plants from growers on forums if you can't find anything at the stores. I'm having someone grow me flame moss, christmas moss, and peacock moss.