We have to really watch our invoices. Our main supplier uses a computer system, but somehow our prices still fluxuate. Usually only on items have have negotiated a better price on. Like a recessed can at $8.15 will somehow slip back to $11.40. We call and they correct it. It will stay at $8.15 for a month or so, then somehow it goes back to $11.40. We save $300 or so every month just by reviewing the invoices before we pay.
