That seems a little steep unless like Scott said you went with the K&N option. As for oil goes, I never had a problem with the recommended Mobile 1 oil 15W50 and ran it until I increased the horse power. The Shell Rotella is good to start a burn pile with or say to lubricate bicycle chains.
Good oil is a lot cheaper then good engine parts!!!!
I can not speak for Caster oil But suspect it is good. I think Triumph switched because of Sponsor $$$$$
I spend a wee bit more on filters and use the Purolator PSL14610 Synthetic filters at about 9.50 a piece.
As for oil I spend a wee bit more but then I do have different components the the OEM engine. Things like heavy valve springs are why I spend a little more on oil. I do want to try the Motul oils as Neville Lush has recommended their brand. He has been into countless Rocket engines, so his choices are based on experience!!!!!!!!