Excel Database Help

I have a complex database file that the users require to be in excel. I have created a master part list and the attached sheets in the workbook are for loading Bill of Materials (BOMs) into. The attached BOM sheets have formulas which reference the Master Part List via VLOOKUP formulas and there are also complex macros. I would appreciate help with some or all of the following:

1)find the lowest price on the parts master
2)create an order of operations with which to populate one column on the BOM sheet (for example: first search for most recent price, if not then lowest price, if not then a particular vendor, etc...
3)create buttons to execute 2)

I know I am asking for a lot and if anyone can help with a small fragment of the above, I would be so eternally grateful!!!