which website is best for outside United States INTRAnational airline tickets?

[rnmcd]

My dad is looking to fly from Renosa, Mexico to Cacun, Mexico.

He lives in Texas but is considering driving to Renosa then flying to Cancun if it's cheaper than flying from Mission, Texas to Cancun, Mexico.

Thanks.

 

[rnmcd]

^

 

[Sphexi]

I think you can do that with Travelocity, some sites don't allow you to purchase tickets originating outside the US.