hi, i'm new here.
I would seriously talk with them, and let them know what you can offer at the time is not what is standard.
thankfully i haven't paid anything for this other than gas to get to training!
I would consult with them right now and makesure everything is understood and there are no miscommunications.
I only say this because once you do start working, it is so easy to get sucked in to the point that you dont realize just how much you are having to give up to finish the job.
If the job is more demanding than what you had originally anticipated, now is the time to bow out.