I would think you'd get more out of numerous smaller upgrades, then the one massive upgrade.
But that depends on prices on your server.

A lot of the iLV 200 stuff should be pretty cheap.

If you can get into a few Naxx10 runs for badges, some of the gear will be ups for you, and the badges might add up to a piece too.

The random dungeon tool is excellent too, as people cannot "gear score" you, prior to your joining the group.

If you gear is at least, say crit immune, and 20k health buffed, you have the same gear everyone else had when we were all just reaching 80th. And heroics were doable then.