LaserCutCard has reconfigured their Ratel 90 kit to have just one turret so the price is lower.
From the announcement:
LaserCutCard have re-released their Ratel kit with only a single turret rather than all three. This has brought the price down from $24.50 to $19.50.
It is also available as the Ratel Platoon (3 x Ratel for $45)