How come Redline Diesel Fuel Catalyst is so expensive in Partshop? ($6.00/bottle) Pepboys used to carry it for only about $4.50/bottle. If I buy a whole case (assuming a case is about 12 bottles) can I get a discount?

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Frank
84 500SEL EURO 101K ( JUST LIKE MY 1ST WIFE. GLAD TO GET RID OF HER! )
85 300D 310K (sold)
90 350SDL 184K sold
83 300D 118K (sold)
88 300E 153k (sold)
93 400E 105K (sold)