It will cost you more if you buy that clothing. So it's better if you get this.
What is the price of this book?
I'm not so badly-off to live in pavements. I have a small house near my workplace.
I present a pair of shirts and pants to my brother for his birthday.

Please correct my sentences.
It would cost you more to buy that garment so you had better buy this one.
How much is this book? / How much does this book cost?
I'm not so poor that I have to live on the street. I have a small house near my workplace.
I'll give a couple of shirts and a pair of pants to my brother as a birthday present.
Students: We have free audio pronunciation exercises.
Thank you Cool Breeze.

"What is the price of 'something'" is more common in India, at least in my groups.

Now, is the sentence "What is the price of the pen" really incorrect?
User_garyNow, is the sentence "What is the price of the pen" really incorrect?

The sentence is absolutely grammatical. I wouldn't use the price of the pen if I were about to buy a pen in a shop, though. In my experience people usually just say: How much is a/the pen? The choice of the article depends on the context. English is a language of fixed phrases and very often one has little choice. A deviation from what is usually said is normally understood but may sound unnatural.
The price of the pen would be natural to my ear in a sentence like this: That would double the price of the pen! I don't know what natives think of this. Perhaps we'll get an opinion from one of them.
This reminds me of an English girl who worked as a barmaid in an international bar in Helsinki. She had been here for some time and had acquired a working knowledge of Finnish before she began on her job. After having worked for a couple of months she told me she would never learn all the expressions and words people used just to order a pint of beer! Emotion: big smile
I had never given much thought to that and so it made me think of the various collocations of words people use in that context. I quickly came up with about 15 different ways to order a pint of beer, ways that are really used in real life, but of course there are more of them. No wonder she was perplexed! Emotion: smile