Level 40 is where Paladins get to wear Plate armor, and it pays to invest in that. Assuming you go for the heirloom chest and shoulders (which are very, very good) your best bet would be to get a hold or check the AH for any plate armor with the "of the bear" suffix, meaning it gives Strength and Stamina. "Of the Tiger" is also good, since it adds Agility. This gives you a higher Crit rating.
There will be a lot of blue-quality items available on the Auction House, but it's best not to spend money on them. You will outlevel them very fast, meaning they are not very good quality for money.
If you do want better equipment with minimal expense, run a few random dungeons at your level to obtain reasonable blue-quality Plate armor.
It is certainly possible, but difficult. Retribution paladins have a lot of burst damage and survival cooldowns, and holy paladins have a lot of burst healing and survival cooldowns. Neither would be able to run the other out of mana, and kiting would be useless. Retribution paladins would stun the holy paladin as they are casting their heals, hoping to kill them before they will be able to heal themselves again. Holy paladins would keep themselves alive for a while, hoping to kill the retribution paladins with Consecrate. Chances for the holy paladin would be rather slim.
The next level would be rune armor.
Contribution, retribution is a punishment.
I sher would but how and what kind of armor
I would prefer evolved shaman it is way better then paladin by overall spells.
In World of Warcraft only 2 classes use Holy Magic: the Priest and the Paladin. Since the cap on character level is presently 70 (to go to 80 with next expansion pack), the 'highest ranking user' of Holy Magic would be a level 70 Paladin or a level 70 Priest. As to strength, the Holy Priest has more efficient and stronger heals, the Paladin has better attack abilities against the Undead; both of which require Holy Magic to be used.
MOPP Level 3
MOPP Level 4
mop level 3
MOPP Level 3
Mopp level 4
MOPP Level 4