It's a bit like the proverbial piece of string. Steve's prices are about the same as they were fetching at Selby last week.
However your best quality will refer to something like a well fleshed suffolk or texel cross, and the plain ones are most likely mules.
So presuming your barren one is quite fat (for a mule), then I would have thought £50 about right.
However, your other 2, having presumably raised triplets, are unlikely to carry much flesh at the moment so would fetch a lot less as culls. So I would have thought you'd be doing well to get £60 for what are, or soon will be, broken mouthed ewes.
Just a thought though - why sell your friend an old barren sheep? Wouldn't he be better with one that he can get a few more lambs off?