After spending over 14,000 gold, I have built 5 decent RCs
Selisian Arbalests Special Forces 80 80-5 / 70
Selisian Rangers Archers 50 65-4 / 80
Selisian Armoured Guards Infantry 65 65 / 75
Selisian Ember Guards Infantry 45 80 / 65
Selisian Black Guards Mixed Infantry 60 90-3 / 75
Not sure how much more gold I will spend but it seems it is getting pretty damn hard to build RCs after 5... Now I need to save up for 2 weeks to try once.