its all about the space! not many people have room for a wreck.
but to give you an idea...I got around $2.5k for the parts off my 260Z 2+2, but had zero interest when the entire car was advertised for $1k. Sure, a fair bit of work went into dismantling, but it does give you an idea of how pricey the parts can get, given alot of stuff was sold significantly cheaper than what you would pay from a zed wrecker. Also, I had no front end panels, which would be worth easily $600 in good cond (bonnet, guards, headlight buckets, indicators, valance, bumper etc) although I did have a few sought after bits like the electronic dizzy.
If you have room, the wreck is the way to go!