There are so many companies which provide us the convenience to have any product by way of crediting. The question is whether the crediting are allowed in islam stuff? If allowed What percentage of gains can they take?
The difference between the buy now price and the buy now, pay later price is the interest element. Credit sales typically work by giving you the product now and the finance company lending you the money to pay for it now. You then owe the finance company the capital element ($200 in your example) as well as the interest element ($300-$200=$100 as per your example)
Riba is obviously haraam.
if interest is involved in anyway, it is not permitted in Islam The only way you can buy things and pay them off Islamically is if the retailer allows you to pay the amount back in exactly the same amount as you would have paid for it if you bought it cash.
For Instance there are some clothing retailers here in South Africa that allow you to pay your goods off for the cash price with 0% interest if you complete the payments within 3months. Some retailers even allow you to pay items off without interest for up to a 6month period! but as soon as interest comes in, or any "extra fee" which is really just interest in the first place. Then whether you are receiving or paying, the transaction becomes unlawful.
The prophet (PBUH) is reported to have said; "Riba consists of seventy-three kinds of evil, and the LEAST of them is like sleeping with one's own mother" . [ Ibn Majah , al-Hakim and others].
That should make it just how clear we are supposed to keep ourselves from this.