Which YOM is your car? The engines are different 3S-FSE(older) or 1AZ-FSE(newer until 2008).
for 3S-FSE -
http://www.toyodiy.com/p...A_ST210-AEPGH_1901.html
The plugs to use are:
DENSO -> PK20GR8 - cost me about 1250/- each about 2 years ago at Commercial Motor Spares (www.cms.co.ke). Haven't replaced yet.
or NGK -> BKR6EPA-8 - not sure how much, but that joint where @iKenya mentions should be an NGK outlet.
I prefer the DENSOs
For the 1AZ-FSE -
http://www.toyodiy.com/p..._AZT240-AEXGH_1901.html
The plugs to use are:
DENSO -> SK20BGR11 - not sure of the price but I suspect would be around the figures quoted previously.
This would be useful (not just for Toyota):
Denso Plugs List (Ex Japan):
http://www.denso.co.jp/c...;filename=maker6jpn.csv
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Side note - using the wrong plugs especially on a D4 is *not* a good idea. Genuine parts may be more expensive but you won't need to replace them often.