because my service is cheaper.
Okay, good. But it is worth knowing for newbies that cheaper does not mean it can not be a scam. Something like this has been linked to scam in the past. Not just one or two but numerous scam.
It would be good for people to use escrow. We have many escrow service providers on this forum. Anyone of them can be used.
Lists of reputed escrow service providers:
https://bitcointalk.org/index.php?topic=5047302But the person is still at his or her risk because service like this are not trusted.
Using the official payment is the best to avoid stories that touch.