Since the equipment is supplied, I would charge by the hour.

I think I pay by the hour… currently $65/hr … to the owner/operator of the equipment. Our soil is extremely rocky and very tough on equipment.

I previously paid $0.10/sq ft for tilling good garden soil — owner supplied equipment and labor.

I think I wouldn’t say “… all I have to do is…”. If you’re going to till and actually build a garden – that involves quiet a bit of sweat and time to get it right. I strongly suggest that you talk over what exactly their idea of “fix” is. Is it till and rake smooth? Or is it till, rake out grass/weed clumps, level, and amend with compost or other organic matter?

Since they are providing the equipment and gas – you are selling your time and your muscles. Where you live influences the going rate. You can charge by the hour or by the job, but by the job is most common. Try looking through local classified ads to get a feel for what manual labor goes for, then look over the area to get an idea of how many hours you think you’ll need to get it done correctly.

I agree with AnnR…..
I know all about the “hard work” in getting a garden going..and all. And the one your going to work its big?…..Yes by all means…check out those adds And it wouldn’t hurt to call a few businesses…..and ask how much they would charge to till the size your going till…..and they will tell you.

good luck