10 years ago when I bought mine, these were the "retail" prices.
25500011 stage 1 3.8 $771.30
25500015 stage 1 4.1 $771.30
25500013 stage 2 3.8 $814.50
25500017 stage 2 4.1 was not listed in this catalog
25500155 on center S2 3.8 $1575.00
25500152 on center S2 4.1 $1575.00