Can't say in canada but if I was buying parts here...
1/4" Automotive fuel hose $20 for 25'.
Mikuni carb kit $46, needle and seat $16.
Fuel selector $25.
Fuel Strainer $25.
Carb Base gasket $8.
Probably $20 is shop supplies so figure total parts at $175 and that is using all OEM parts.
Labor 2 hours at $100 you are looking at $375 with no markup on parts so at $350 he is not using OEM quality parts.