When you add your inventory items, there is an 'item type' field that can be set to 'kit.' If you are not familiar with the term, a kit is a bundle of items that are sold together on the same listing.
Once you have completed set up the individual inventory items that go into the kit (these are called kit components, and you can also sell these separately outside the kit), you can use the edit kit function..its on the 'Manage Inventory Items' page...to associate the kit components with the kit identity they can be sold as.
There is another item type called assembly in which the assembly component items cannot be sold separately but only in the form of the assembly.
I think the kit fits the model of what you said you wanted to do better than the assembly does.
We have some tutorials on inventory...here is the one covering adding items Add Inventory Items Tutorial
Hope this helps.