This page describes four Gibson flat top acoustics, the J40, J45, J50 and J55 - though the J50 is not pictured.
UK prices (1981) were as follow: J40, £789; J45, J50 and J55, £829.
$5500
$4200
$2750
$700
$8995
$79
$8899
$4250
$670
$795
$1695
$6300
$6500
$3750
$5000
$1199
$2199
$4985
$3900