Just bought oil and plugs for my bricks at Walmart.
$21.36 per Gallon for Shell Rotella T6 Full Synthetic 5W40.
$2.92 each for NGK plugs. Order online for store pickup. Takes a couple days to get them in. Use the NGK stock numbers for the best prices. 7839 for K75 and early K100 that use D7EA. 7912 for 4Valve K100 that use DR7EA. Don't use the D7EA or DR7EA numbers or you will get a price of $6.96 each(don't ask me why).
I haven't ordered any yet, but I think there are similar deals on Mobil 1 transmission gear oil and oil filters.