I would like to play WoTR someday and would like to know how to plan my purchases. Besides movement trays, how many figures on average do I need for a decent army? Thanks in advance for your helpful advice.

Get as many common foot troops as possible. At least enough for 12 companies (96 figs). That's a solid base and you can fill in what figs you have in SBG to make a formation. Maybe aim for 2 companies for archers, 3c for Calvary and 4c for infantry. That should be a solid enough army.

You can think of using proxies as well. Warriors of Minas Tirith for example, sometimes I choose not to field any Archers of Minas Tirith and instead proxy Osgiliath Veterans. More extensively you can proxy Rohan Warriors to Isengard as Dunlendings with Shields or go with a troop without a model in Carn Dun Warbard and ally Ruffians. They still look thematic and with Rohan's case you can field both a good and evil army.

_________________
http://drinkingwotr.blogspot.com/ - Links to my CrAzY House Rules, Games and 'poor man's' terrain.

Thanks Slythar. I will aim for your suggested minimum of 12 companies for a particular army.