my opinion:
best weapon seller: forest lands(melee) great trade republic(ranged)
best armor seller: order of the holy cross
best horse seller: black horde/forest land(hard to decide)
best unit seller: east empire/forest land
hope can buy the weapon at lvl 13 alien campaign(rocket launcher,forget the name)
Ps:if you see my badge and theres no raze 1/2 badge,i haven't play it at kongregate,i play it at flonga
how to get all unique characters:
1.Tristan(first character you get) will turn into hero
2.Greg(finish 3 Kongregate special event) will turn into sentinel
3.Adela(win 10 first battle consecutive) will turn into kurestal maiden
4.Chrisstine(hard mode only,have 123456 coins,then search in city) will turn into assasin
5.thyton/lancer (will find in a tournament) will turn into gladiator/berseker
6.corthello(lose some battle) will turn into bishop
7.irvine(honored by blades of glory/golden scales) will turn into sniper
 "Earn to Die"){kind=icon}
 "Warfare 1944"){kind=icon}
 "The Last Stand: Dead Zone"){kind=icon}
 "The King's League: Odyssey"){kind=icon}
 "Feudalism II"){kind=icon}
 "Wartune"){kind=icon}
 "Raze 2"){kind=icon}
 "Contract Wars"){kind=icon}
 "Scene of the Crime: Dream of Murder"){kind=icon}