I bought vs. I have bought

[Polyester]

Are the following sentences wrong?

I bought the headphone last week. It's quite expensive.

Have you bought a new car?

 

[GoesStation]

Are the following sentences wrong?

I bought the headphones last week. [STRIKE]It's[/STRIKE] They were quite expensive.

Have you bought a new car?

With my corrections, they're okay.

 

[tedmc]

Polyester
You wrote the two sentences together.
How are the headphones related to the car?

 

[teechar]

Why do the two sentences need to be related? Perhaps they're not.

 

[Tdol]

What's the difference you're trying to show?

 

[tedmc]

Why do the two sentences need to be related? Perhaps they're not.

If they are not, then number them 1 and 2.

 

[Charlie Bernstein]

Polyester
You wrote the two sentences together.
How are the headphones related to the car?

Actually, they're not together. They're two separate lines. I take that to mean that they're independent of each other.