I like the Gloves, Shoulders, Helm and Chest from T5. I think the legs are up for debate. If you are likely to get them soon, just go for it and use them. The itemization on the tier pieces is generally a bit better than badge gear. If not, then get some sunguard legplates as mentioned before. The expertise is quite nice, you should probably pick these up regardless.
The legs are probably the last piece of T5 I'd pick up, after all my healers and DPS gets them. We have T5-equivalent gear in badge gear (well, T6 if you have the sunguard).
The order of T5 that I'd look for are shoulders > helm > gloves > chest > legs. There's no equal for the shoulders, the helm is good for non-engineers, the gloves aren't as good as bonefist most of the time, the chest isn't as good as the 2.4 badge chest, and the legs aren't as good as the 2.3 or 2.4 badge most of the time (ie, they're just situational).