I compiled a list of NGK spark plugs and thought it might be helpful to some.
All from
www.rockauto.com
P means its a projector tip plug
R means its a resistor plug
I think everyone knows on these plugs the higher number means colder range plug
All prices are for one spark plug.
NGK IRIDIUM
-BPR6EIX (NGK 6637). $6.47
-BR7EIX (NGK 6664). $6.48
-BR8EIX (NGK 6747, 5044). $6.48
-BR9EIX. (NGK 3089, 3981). $6.48
NON-PROJECTOR, NON-RESISTOR
-B6ES. (NGK 7432). $1.59
-B7ES. (NGK 1111). $1.69
-B8ES. (NGK 2411). $1.69
-B9ES. (NGK 2611). $1.69
-B10ES. (NGK 7928). $1.69
RESISTOR
-BR6ES. (NGK 4922). $1.59
-BR7ES. (NGK 5122). $1.69
-BR8ES. (NGK 5422). $1.70
-BR9ES. (NGK 3194). $1.70
-BR10ES. (NGK 4832). $1.70
PROJECTOR AND RESISTOR
-BPR6ES. (NGK 7131). $1.60
-BPR7ES. (NGK 5534). $1.59
-BPR7ES. (NGK 2023). $1.74
-BPR8ES. (NGK 3923). $1.59
-BPR9ES. (NGK 7788). $1.70