Who doesn't like food that comes out of a cart? I always think its some of the most decadent, delicious stuff you can find and ramen noodles are no exception. This isn't a dish I eat much in the States, but I did like the one we had here. (Tokushima is famous for udon, not ramen) . The soup is made from two kinds of paste stock, one of which I think is a kind of fresh soy, added with noodles and a thin slide of pork as well as some green onion. Its really quite tasty, and almost a meal unto itself, but should only set you back by about Y400, maybe $3.75.
Ramen carts aren't all that common but they aren't all that rare either. You should be able to find one anywhere people gather.