Inventory tracking and billing

Let's say I sell widgets to wholesale & retail customers. There are 12 models (4 colors and 3 sizes), each which carry 1 common label & 1 model-specific label,insert &box. I have 4 mfrs (widget,label,insert,box). Widgets cost me from $4 to $12 ea, labels and inserts from 3-12 cents ea and boxes $4 ea. Need recommendation for setup for inventory & billing, ie, assemblies, groups, etc.