I really like this idea. 
Managers that wants to rebuild their roster can sell and buy not all in once - users need to know how to rebuild their team step by step. 
The only issue I do see is if a day will come and a player will be worth 10M or more. but I really don't think that's something that should happen in the near future. This feature should be considering market prices. 
                                
                                
                                
                                
                                
                                
                                    "Did you miss me??? - "With every bullet so far..." Al Bundy