Motohansa are only expensive if you know someone who is as good and cheaper , but it sounds like you dont.
I have sent them a drive shaft and a final drive over from Adelaide , they stuck to the quote and work was perfect .
Even with shipping it was cheaper than the local crooks and bodgers were quoting.
If you need the head done I would order the parts from Motobins first - their complete kit is less than BMW Oz charge for one exhaust valve.
Then take it to any decent auto head shop, will a list of exactly what you want done.
I have had great difficulty finding anyone other than Motohansa who can do the specialist machining / repair with any degree of competance, so I recon you are just going to have to lump it- no sense in trying to save a few bucks and getting a back yard bodger to stuff it up.
Adelaide Hills, Australia. 93 R100 GS, 77 R75/7 ,70 BSA B44VS, , 86 R80 G/S PD, 95 BMW Funduro F650 ST