this is the best piece for your price range.

[tufguy]

Customer: I need to buy a laptop.
Salesman: What is your price range sir?
Customer: $5000.
Salesman: (Showing a laptop to him) Sir, this is the best piece for your price range.

Please check my sentences.

 

[emsr2d2]

Customer: I need to buy a laptop.
Salesman: What is your price range, sir?
Customer: $5000.
Salesman no colon here (Showing a laptop to him)​: Sir, this is the best [STRIKE]piece[/STRIKE] one/laptop [STRIKE]for[/STRIKE] in your price range.

Please check my sentences.

$5000 isn't really a range. A range is usually between one number/amount and another. However, your $5000 would probably be taken to mean "My range goes from nothing to $5000" so it's not impossible.
We don't call a laptop a "piece".

 

[teechar]

Customer: (Anything) up to $5000.

.

 

[Skrej]

I'd probably use 'model' or maybe 'unit' in lieu of 'piece'. 'Machine' is fairly common when referring to desktops, but I'm not sure if I've heard it used for laptops.