A FlyerTalk Posting Legend
Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 102,617
These price differences sound like consolidator fares or worse.
However, has the OP checked out the credentials of the travel agency? Could they be a broker for FF tickets? That's something you don't want to do.