are there grammatical mistakes or unnatural expressions?

When I went to Ikebukuro yesterday, I found a big movie theater for the first time. I was like “has this been here before?” This means going to Shinjuku to watch a movie is a waste of time and money, doesn’t it? Give me back traveling expenses, you know, as the train fare from Takadanobaba to Ikebukuro is lower than Shinjuku. No, I’ll take it back. I usually go to Ikebukuro by foot, so I just felt like I hardly paid for it.

(Shinjuku, Ikebukuro, and Takadanobaba are the names of staions in Tokyo.)

> This means going to Shinjuku to watch a movie is a waste of time and money, doesn’t it?

In this situation, saying "doesn't it" is, I think, actually technically more correct, but it sounds a bit strange. Most English speakers would actually say "isn't it" instead.

> Give me back traveling expenses, you know, as the train fare from Takadanobaba to Ikebukuro is lower than Shinjuku.

I think it should say "Give me back my traveling expenses". This also basically seems to be an exclamation, so I would end it with an exclamation point and do the rest as a new sentence. I would also say "because" or "since" instead of "as" in this case.

> No, I’ll take it back. I usually go to Ikebukuro by foot, so I just felt like I hardly paid for it.

I think it is more commonly said as "I take it back" or in this case (since it is something you just said) "I take that back". Also, using past tense ("I just felt like ...") makes it sound like you don't feel that way anymore. Also, using "just" makes it sound like you are using that as the reason for your previous statement, which doesn't make much sense. I would just say this as "so I feel like I hardly paid for it". I might also add "anyway" on the end to emphasize more that that's the reason you're taking back your previous statement.

So:

When I went to Ikebukuro yesterday, I found a big movie theater for the first time. I was like “has this been here before?” This means going to Shinjuku to watch a movie is a waste of time and money, isn't it? Give me back my traveling expenses! You know, since the train fare from Takadanobaba to Ikebukuro is lower than to Shinjuku. No, I take that back. I usually go to Ikebukuro by foot, so I feel like I hardly paid for it, anyway.

I hope this helps..