So if there is roughly 97 Members worlds to hop to, excluding the fact that there might be other people buying grapes aswell: lets say roughly it takes you 10 seconds to hop and buy 6 grapes.
97 x 6 = 582 grapes if you hop to each world. 97 x 10 divided by 60 for lands at a full hop run taking 16.66 minutes.
**lets take away the world hop limit.**
each full run of 582 grapes will cost you: 582 gold at 1 gp a piece.
It will take 10.30 full runs to achieve 6k grapes purchased.
16.66 x 10 = 171.75 minutes to completion = 2.86 hours.
**remember this is at peak performance and no world hop limit, really this task will take a little longer**
I would say just because this is a menial task, I'll have you PM/reply below your offer after seeing these numbers.
**You pay for Grape costs as well.**