Just got lv 30 last night @_@:
Armor:
Head: Emperor Hairpin
Body: Mercenary Captain Doublet
Hands: Scentless Armlets
Legs: Mercenary Captain Hose
Feet: Mercenary Captain Gaiters
Shield: Frost Shield
Back: Nomad's Mantle
Waist: Mercenary Captain Belt
Rings: 2x Balance Rings
Neck: Spike Necklace
Earrings: 2x Dodge Earring
Weapons:
Sword: Mithran Scimitar
Dagger: Mercenary Captain Kuhkri
Ranged: Chakram
I've probably been spending too much time farming gil for equipment and too little time leveling.

Overall, I think its probably better to level to where you can hunt things like the Valkrum Emperor with some friends than spend aeons farming gil to buy them in most cases. Given my general ability to find the crappiest groups possible (not all of them, the good ones are really good and the bad ones are really bad - sorta like a evil McBLT), I don't think being decently equipped has ever affected getting invites (but that just goes to show how bad my xp grouping has been :/ ). It does get you hordes of examine spam though. <_<
Not having partied with other thieves in a while I'm not sure if all that extra dex and +evasion really pays off. I like to think it does, but I don't really have a point of comparison. I had been considering saving up for a pair of Winged Boots, but I couldn't resist going and buying stuff to level RNG, doh. Other than that I was planning on getting a pair of Drone Earrings at 35 and a pair of Deft Rings at 36, whenever I get around to leveling THF again. Maybe a Federation Kuhkri at 34 if one is for sale; if can sell my Scimitar for what I paid for it I'll break even between the two. @_@
One thing I've sorta been wondering about is where to upgrade armor before Brigadine at 45. There's Gambison and whatnot, but I was sorta wondering whether the stat bonuses are worth more than the added DEF at that level or vice versa.
-edited because I noticed I was leaving words out of sentences XD