I would be very surprised if you could find a shop that would be willing to use oil that you provide. However, I pay about $50 (US) for a lube service with Castrol GTX. $62 Canadian doesn't sound too bad.
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K