Tough choices need to be made for units and large numbers I think. 35 minis multiplied by whatever you can charge will still rely on the persons wallet having enough money. Do you need money or can you stand your ground? I ask because even at the insanely low price of £10 a mini (and i'm not suggesting this price!) you are still asking for £350 of someones money which is no small number... even £20 a mini is low and that's £700!
The time it will take to make the set "worth" £700 to someone will, I suspect, be massive so the way to look at it is to ask yourself:
How can I speed up my painting by batching minis up... air brushing, base colours, not agreeing to do fancy bases for the minis and freehand that will eat my time away.
Will I enjoy painting them and if so, can I offset the price by being happy to paint them?
Can I get the person who wants them painted to do any of the work?
How much will the person who wants them painted be able to sustain in terms of cost?
All I know is that I asked someone to paint a blood bowl team for me ages ago and they started off ok but were defeated by the scale of the task and the realisation that painting units is as much of a skill as painting super fancy stuff. Sure you won't get 9.8 CMON scores for units but if you can bust out a totally solid squad a night, you have great talent!