I guess we'll have to get more information on the budget. My assumption was for alum framesets. There's a Defy Composite, which is great but there's also a TCR Composite (different from TCR Advanced and SL) which is just slightly more expensive than the Defy Comp
I'd say about 10-15% price difference only between the two models, whether aluxx or composite
As pointed by Ricecooker, Defy can be a race bike on it's own not just an exercise bike.