You have raised a highly pertinent point "where's ya cash coming from?"
I too have that core group of highly priced Mids, couple of reasons, good scoring and hopefully no upgrades.
For the moment I have:
Hill....................D5
Oliver..............M5
Naismith........R2
D. Smith.........F5
I'm seeing the best cash generating rookies in the mids, so I have Rowell, Greene and Pickett on the field. Gould (for now) at D6, and Hosie at F6.
But by running a team like this requires me to have probably all of my bench rookies earning $, currently it's not looking that way with, Williams, Keane, Rivers, Mahony, Budarick, Comben, Rankine and Cameron. My fallback position is to lose Whitfield and spend a bit more on the bench rookies, which is probably not going to be enough. I know it's frowned upon to have high priced rookies on the bench, but I might have to go that way to, firstly provide cash and secondly to provide better cover.