I spent the past hour+ on trying to catch up with the PtP threads to see if anybody came up with this before; sorry if they did and I missed it.
The basic idea
 There’s a mandatory flat fee for PUTs. It depends on the current network status yada yada.
 If somebody wants to make money with their content, they can pay a premium.
 The more they pay, the more of the farming reward they get.
Basically, farmers would get more initially if they had to give up some of it later.
I’ll use this formula:
AP
R = 
AP + M
Where:
 R is the ratio of the reward that goes to the owner instead of the farmer
 A is the amount the owner paid for the PUT (or added later, because we could)
 P is our “flat fee”: the current minimal cost of a PUT
 M is a hardcoded constant to set the diminishing returns and keep R under 100%
Example
Let’s say 1GB is P=1 coin, and M=19 to get 5% for double price (just an example!)
 If I paid the minimum
A=1
coin, I wouldn’t get anything:
R = (AP)/(AP+M) = (11)/(11+19) = 0
, which is 0% as expected.  But I want to get paid, so I pay
A=2
coins instead. This way I get:
R = (AP)/(AP+M) = (21)/(21+19) = 1/20
, which is 5%  I pay 2 more coins, so now I have
A=4
total:
R = (AP)/(AP+M) = (31)/(41+19) = 2/22
, which is about 9.1%  The price goes up, and now 1GB is
P=2
coins. With myA=4
coins, now I get:
R = (AP)/(AP+M) = (32)/(42+19) = 1/23
, which is only about 4.3%  I pay 20 more coins because I want to get rich;
A=24
, so:
R = (AP)/(AP+M) = (242)/(242+19) = 22/41
, which is abou 53.7%  Not enough! 20 more!
A=44
, so:
R = (AP)/(AP+M) = (442)/(442+19) = 42/61
, WHAAAT? ONLY 68.9%???
Oh well, those diminishing returns
Random Extensions to the Idea

The extra coins could decay exponentially with time, and then discarded when a limit is reached. If you want to keep getting paid, then keep paying for it, basically. In effect, content left alone would revert to “free” (100% to the farmer) after some time.

It would be super lovely if GETs could cover for the premium. Free content (paid only the flat fee) would be free to get, others would cost the same the owner would receive. This would of course change the equation because no longer would it be necessary to keep the ratio under 100%