As it stands, there's little (WoW Gold)or no gear focused on Spelldamage that has Melee Crit/Agility and/or Melee Hit on it, by focused, I mean as its main stat. Instead you'll find Spell Crit and Spell Hit on those items, which as previously mentioned are more or less useless for retri-spec.

On the other hand, usually all gear with Str/AP are loaded with the Melee Crit/Agility and Melee Hit which you need.

That's the 2nd reason why Spelldamage loses out (WoW Gold)to Str/AP, simply due to itemization.
Spell Hit remains the Achilles’ heel of retri paladin itemization however. You won't find it on gear that improves your other retri attacks, and going for pure Spell Hit items will just gimp your overall gear. The buff to the 1 retri spell that uses it (JoC) is not worth it. "Warrior gear?": A trend that is sometimes observed is paladins going for pure "warrior" damage plate. While it usually has great Str/AP, Melee Crit and Melee Hit, it does take its toll on your mana pool and your Spell damage. Without mana there's no damage and while Spell damage is not a must, every bit of it helps and buffs your overall damage.

"Warrior gear" is therefore not advised. It is usable in moderation, you can use some pieces until you get better items which are actually designed for Retribution paladins.

What gear to get?
Basically the T4/T5 retri sets or the Arena 1/Arena 2 retri (preferred) sets are atm what you'll want to go for, they have the perfect balance of stats.

There are lower level blues in dungeons that have a similar talent spread that you can also go for, until you acquire these epics.

What about +Hit?
If you've followed this guide so far, you'll probably notice a lack of Melee Hit in the suggested gear. This should be balanced by getting this stat on your Neck/Cape/Rings/Trinket slots or Gem sockets/enchants if needed. You should aim for 5-6% hit for PvP and ~8% for PvE.

What stats to plan for?
Basically when you start off gathering your(Gold WoW) retri set, you'll want to shoot for the following:

Melee Hit: ~5% for PvP, ~8-9% for PvE. Remember if you keep missing, you aren't going to do enough damage. Don't go over these caps however or it's wasted item stats. There's always a theoretical miss chance of 1% however.