A "Definition Function" for Vendor Price

Hello everybody ...
I am still wondering ... will ever ben available a FUNCTION in order to set the price we pay to a vendor for a job?
I mean ... I would love it we could take the JOB PRICE - x% and divided it by 2 for example?
Will this ever be possible?

More than this, I have another doubt:

Let's say I have a partner in translations. We make x jobs per month, let's say 100 or to make it easy just 10 ...

Right now, what I do is:
1 - I send a job offer to a customer and when he/she accept it I do My_Price - Taxes
2 - I split by 2 this amount and I put this in the Job Assignemt ...

It is boring! Really!
I am wondering ... Could I ever have 10 jobs with 1 assignment each but being able to do NOT calculate assignment price every time ???

For example, if me and my partners do 100 jobs per months, would it be possible to register 1 invoice only per month for this partner? Non managing everytime 1 assigment price per each job ???

I know it sound wierd but ... I am thinking how to optimize my workflow ...
From one hand, having 1 assignment (or more, of course) per job is very useful ...
From another hand, it is time consuming! If we could have 100 jobs per month and only on this CUMULATIVE group of job be able to set 1 single "assignment" or 1 single "vendor invoice" that would be something cool, imho ...

Sorry for this stupid questions!

THANK YOU

Pietro