Fix error when labproduct's price is Decimal('0.00')
Fix error when labproduct's price is Decimal('0.00')

This value is falsish, and boolean logic cannot be used

veroc/Bika-LIMS,rockfruit/bika.lims,labsanmartin/Bika-LIMS,labsanmartin/Bika-LIMS,labsanmartin/Bika-LIMS,veroc/Bika-LIMS,rockfruit/bika.lims,veroc/Bika-LIMS