In Islam it is forbidden to trick anyone even if this person is non-Muslim or unbeliever. This applies to products prices and any type of trade. 

Swindling an Unbeliever in a Sale

Similar Questions

• Using tricks against an unbeliever in trade;

• Cheating unbelievers in price.

The Issue

A Muslim living in a non-Muslim country may try to trick unbelievers when he sells items to them. For example, when selling a car the Muslim vendor may ask another Muslim to bid a higher price against non-Muslims, although they have no intention of buying it, to secure a better price for their fellow Muslim.

Ruling

It is not permissible for a Muslim to resort to swindling anyone, even though he may be an unbeliever. This is the ruling given by Shaikh Muhammad ibn Uthaimeen.[1]

Sources

• Fatawa al-Aqaliyyat al-Muslimah, by a group of scholars.

• Khalid Abd al-Qadir, Fiqh al-Aqaliyyat al-Muslimah.