I supplied my own oil, but not to save. My motive was to ensure that mine got the correct oil!
I asked my dealer's staff twice specifically what oil they were going to use and twice they were unable/unwilling to tell me. This led me to believe that they didn't know and didn't care so I asked if it was OK to bring my own and was told that this was OK.
Which was fine until I turned up with the car and some Full Synth SP/GF6, that's when a shit storm started about it even though that spec is superior to the SN+ they intended to use (but were unable to tell me about initially).
It's been resolved now but I could have done without the hassle.
The problem appears to be that my manual, and the oil filler cap specifies SP/GF6 but Toyota is having trouble getting this with their packaging and in small quantities. They do have SN+ though and Toyota UK seems to be fudging the issue with a tech bulletin which recommends SN+.
My bill was reduced from £190 to £120 because they didn't supply the oil, but the oil cost about £55.
There might be a general problem with sourcing SP here though.
My first choice was the Petronas one, ordered it but what arrived was SN+, there was no Petronas SP in the country! So they sent a substitute, which I had to return.
Would I bother again? Not now I know that they are using SN+, but I would hope that by next year Toyota UK will have sorted out their supply of SP.