There is also Darksword miniatures which does GoT miniatures:http://darkswordminiatures.com/mainwebsite_html/store2GRRM.htm
There is also this mod coming out for Mount and Blade Warband. Mount and Blade Warband is only about £13 on steam and the mod is going to be free.It would be considerably cheeper then buying aload of new miniatures.
There is a beta for the end of summer and depending on how good your PC is you could have battles between 75 + . The game as standard allows people to have battles which have 150 people in it and there being more reinforcements , after so many die. There is a mod which allows you to increase the size of the battle to the amount your computer can manage though so you could have 250 on each side, or more.
Check the link below so see some of the kick ass armours it has. The mod will allow you to execute other lords, so can kill Roose, the Walders etc . You can also issue battle orders, and raise troops if your a lord, and marry various people. http://forums.taleworlds.com/index.php/topic,194575.0.html