Para saber el número de bandejas que tiene una impresora (y para muchas otras cosas más) podemos utilizar la función del API DeviceCapabilities :

Private Declare Function DeviceCapabilities Lib "winspool.drv" Alias
"DeviceCapabilitiesA" (ByVal lpDeviceName As String, ByVal lpPort As
String, ByVal iIndex As Long, ByVal lpOutput As Any, lpDevMode As Any) As Long

Private Const DC_BINNAMES = 12

Dim NumBandejas As Long

NumBandejas = DeviceCapabilities(Printer.DeviceName, Printer.Port, DC_BINNAMES, ByVal 0&, ByVal 0&)