I won't pollute Mikes thread further;
There were 5 GNs that arrived at Toronto Area dealerships from the late builds in Dec 1987.
I looked at all of them, they were very very close in options and bottom line. Don't recall there being a hardtop in the bunch.
( my sales guy was an old GM top performer and apparently was empowered to round off to the nearest dollar)
From my invoice ( backing out my trade in and discount):
base Regal $14,290
GN package $5,212
concert sound casette $458
remote mirrors $43
tinted glass $170
body side mouldings $75
6 way pwr seat $302
power locks $197
power windows $283
power trunk $54
accent moulding $21
t roof $1,172
pulse wipers $68
lighted sunvisor psgr $78
limited slip $130
block heater $27
tilt steering $155
tungsten headlights $31
headlight chime $23
heavy duty battery $36
power antenna $82
6 speaker system $113
Sub Total $23,020
freight $475
ac tax $100
fee $30
gas $15
rustproofing $349
fabric guard $129
Sub Total $24,118
prov tax $1,688
Grand Total $25,806