For as small as the weekly pay is, the shop prices seem very high. Only the most basic, cheapest item (Zeon's Dopp) won't require a player to save up for weeks.
Your requirements for planetary/region control are also prohibitively expensive. Even the minimum, five bases in one region, would take an Admiral years to afford!
Unless your rewards for RPing are so huge they make a weekly salary unnecessary, I think you need to either lower shop prices, raise salaries, or both.