As a balance druid who does use Tribal Leatherworking, I say it is worth the price. I have done lots of research to determine the best equipment that I could get access to as a Boomkin druid at end game and other than badge rewards, which will require heroic runs, the Windhawk Set trumps everything before the tier sets. There is quite literally only about three pieces of +spell damage leather that drop from bosses in all of the end game raids other than Zul'Aman. The first of these is a set of bracers in Kara. The rest are in Black Temple or Mount Hyjal.
Your other options for gear involve doing PvP, Arenas, and finding suitable cloth pieces. For the gear I am using see my armory link in the sig. I have one badge reward, one PvP reward, one piece from a non-heroic Sethek, the Windhawk set, a crafted helm, and one T4 piece. All of it is leather but not easily come by.
By far the easiest pieces for me to get in terms of the time involved were the 4 crafted leatherworking pieces as all they required was a bit of material farming and then a few Heroic runs for the necessary primal nethers with guild mates.
Also, up to 225 in LW really is aimed at the rogue, hunter, and feral druids for stats. Once you get up closer to 300 you will see some pieces with intellect and spell damage.