One of the things we highly value in our competitive league is that the season start out with as much of a level playing field as possible, however.
So if I was to implement this idea, I think I'd do two things.
1) I'd cap the amount of points that could be purchased, so some guy who is pretty free with his cash doesn't just buy his way into a situation where the odds are really slanted in his favor in terms of draft position.
2) I'd assign a purpose to the $'s that owners who chose NOT to buy more points. For example, maybe everyone is allowed to spend up to $50 on buying points for this purpose, but if they choose not to buy any, then the $50 is added to their salary cap or bidding allocation or whatever. Basically, something that makes it a decision that the owner is making about how to best try and improve their team by contributing these $'s to the prize pool rather than just an exchange of $'s for favoritism in the lottery for draft order.