Or for example make something like div 4 max players wage not more then 20k, div3-35k, div2 50k, div1- no limit...
Part of my point was not to place any restrictions on the teams in BB, except for the national teams. I don't believe the economic restrictions are necessary, as I don't see how a Div. IV team in the USA is going to make much more than $110K on home games, if that. That's about where I topped out when I won my Div. IV championship -- if others make more money in USA Div. IV, speak up.
Now, the issue is that if you stripped down a team in USA Div. IV but could still manage to pull in about $100K per week from home games, you could afford to farm for one superstar player as long as you sold him once he hit about $70 or $80 K, i.e. you could get him up in salary near what you make in revenue before he became too big an economic problem. However, I think your solution creates more problems than it solves. What happens when a player in Div. IV gets good enough to make $30K? Do you take him away from his team? Do you stop paying him more? Do you stop him from training to get better?
That's why I like the idea of controlling what the national teams do, not what the regular teams do. Want realism? The national teams should simply be kept from taking players from farm teams on the ground that such players don't play on the national stage, with real competitive teams, and therefore are not properly representative of their countries' basketball talent. If you want to stretch your finances and lose games to make a great player, fine, but you won't do that and get him on the national team. And have no fear that the BB equivalent of Kobe or LeBron will languish on one of these teams, because they can't afford to keep him and will eventually have to sell him to a real team (which can then put him on the NT).