Here is my new rig setup, r9 280x. Only one piece of it 
Do you think the extra cost of the R9 290x vs the 290 is worth it?
Probably not. But in resale value, maybe?
A 290 hardly isn't worth it though, not when a 710-740kh/s 280x can be had for $100 less. Of course this all assumes you are pre-ordering everything since they're still out of stock most everywhere.