They are still available from any Yamaha dealer.
They have been upgraded from;
http://www.boats.net/parts/detail/yamah ... 72-00.html
To;
http://www.cmsnl.com/products/bushsolid_9038010197/
I do not think you will get cheaper than from the USA supplier though.
As you have not stated where you are in the Galaxy it is hard to decipher what the p+p will cost !
The bush fit is not what I would call critical.
Remove the faceplate from the valve and take measurements of the valve spindle and the faceplate recess.
If you are contemplating turning units from graphite; you should have access to the measuring tools.
Before use the genuine part is soft and malleable and easily fitted ;after exposure to exhaust gasses it is hard and brittle.
Machinable graphite will be hard and brittle in order to withstand tooling,
You may be able to manufacture a special drift to fit the blind end bush if you can machine a replacement from graphite.
Brass would be a better medium.
It is only a simple bush; it does not have to withstand high speed rotation.
If the reassembled valve falls freely under its own weight when a manufactured bush has been installed it will suffice.
I believe I paid £15/17 in the UK last year from the local dealer.
Sent from my keyboard using the English language not some teen text shite from a fooking phone.