Well look at it this way: most machine shops and motorcycle shops charge somewhere from 75-100 dollars per hour. That means your valve seat cutting job is expected to take somewhere around 1.5-2 hours. Does this seem fair to you? If so, then it's a good price.
That seems fair to me, considering that they're cutting multiple angles and they're doing 8 valve seats in about 2 hours. That's just me.
As for the clutch cover gasket: that's a paper gasket yes? If it's in good shape, get some good RTV (Yamabond or Threebond are two of the best for staying set up really well under oil and not getting gooey) and dress the gasket a little in RTV on assembly. Be careful not to goober it up in the case. If the gasket tears at all, replace it. Not worth the money to have to deal with drips.