Barcode Inventory System - Running Inventory

I know through experience that Excel is pretty powerful, but I may be asking too much. I am currently designing a barcode inventory system from the ground up using scanpet (android), excel (2007), and sugarsync.

Right now, I have (3) excel spreadsheets set up as my templates for scanpet: Inventory; Purchase Orders; Add-ons & Returns. When my warehousemen pull orders, they use the Purchase Orders template. They scan the item, fill in the blanks (change quantities), then save and it syncs to sugarsync as excel file. Next order they pull, they start a new spreadsheet. Add-ons & Returns do the same thing, just minor differences in the formatting.

Several times per month, I like to spot check my inventory for accuracy. To do this, I simply load my Inventory template in scanpet, scan the item, then check that the quantity is correct.

My question : Is there any way that I can have my master Inventory spreadsheet reference other workbooks as they are added to the same folder, in order to keep an automatically updated running inventory? I have used VLOOKUP for several of my other spreadsheets and have some experience with Macros, but have no idea where to even start with this project.

ANY help or direction with this would be GREATLY appreciated!

are there any naming protocols on the other workbooks?

scanpet lets me set the prefix to whatever I want, but automatically adds "_(creation date)_(creation time).xls"