Excel 2007 : Custom Series using the drag to fill handle

I have a spreadsheet which is used to check out part numbers. The part numbers are as follows

200100-01
200101-01
200102-01

etc.

The -01 at the end allows using similar numbers for items that may only have minor differences. For instance, maybe they are the same except for color.

Currently when someone wants to take out a new part number, they have to manually enter the new number in the list. In this case, that would be

200103-01
200104-01

Not a big deal if you only need 1 or 2 numbers. If you want 80, then it takes forever. Is there a way to use the fill down function to make this easier? Everything that I have tried so far repeats the numbers in the list rather than creating the next number in the sequence that I want.