I think the first question is, what role are you aiming to play? Healer, DPS, Tank.
Im assuming Healing since you already do that and do it well =)
The next question if that is the case is what is your healing style? Meaning, what spells do you use often, do you downrank them, etc.
Pally healers from what Ive seen can be set up a few ways depending on the style of healing the person is aiming for. Some stack crit and +healing, others stack +int and mp5, so I think a lot of advice would depend on your playstyle.
For immediate upgrades, I would definitely look at some of the S2 PvP stuff as temporary stepping stones.
For weapons, you could go with [item]Gavel of Pure Light[/item] which if you have the rep you can basically buy it now, or [item]Merciless Gladiator's Salvation[/item] might be a better route due to the higher stats. It lacks the mp5, but it makes up for it in higher healing and int.
For your belt, you are pretty much limited to drops from Kara/TK/ZA or [item]35160[/item]. Solarian drops [item]29965[/item] and Hex Lord Malacrass drops [item]33446[/item].
Leggings you can prob have an easier time getting [item]29063[/item] off Gruul's token drops, or [item]33518[/item] which is 75 badges at the vendor or [item]30137[/item] from Fathom-Lord in SSC.
For shoulders I would work for [item]30138[/item] off Void Reaver's token drop honestly. We kill him every week so its not long before everyone will have T5, you'll have a pretty easy time getting those.
Truthfully tho, I would take advice from Cap or our other pally healers more than me as I can only offer help based on outside observation as Paladin is the only class I havent been able to get into myself so I dont have much first hand experience with it =(