If you can't DIY it you better have a good job to pay for something like that.
I would guess around $250 ~$450.? 10~15 yrs ago it cost about $25.00 'per hole' to have valve seats cut, valve guide replacement $20 each, cutting, etc extra. $200 or more a set ( think that may be with 45deg seats done?) To do it properly is going to take at least 4 hrs so I guess it depends on labor rates?
Unless you know the shop very well I would be very wary of a cheep price. You can get automotive done cheaper as they can set up for at least 8 valves of much larger diameter, many automotive shops won't even look at motorcycle stuff and many bike shops are only interested in high dollar restorations or Harley's (in which case equipment would be too big) If I could get my head together (and I mean mine not a cylinder head) I would offer but I've had a 360 head here about 3 yrs so far. I made a set of aluminum bronze guides but my step-grandson has hidden them somewhere, he loves the garage and workshop. Also looking into 35mm intakes from something different, may not work but I'll find out.
I think I have ordinary bearing bronze but would prefer to use 'the good stuff', particularly since they are already done. If you do fit new guide, make sure head is heated to about 250f, and guide is either drawn in with bol and shaped washer on valve seat or pressed in with correct holder sitting on valve seat. Hammering the iron guides is likely to crack them even though it was 'correct' in 1970's.