as to price you may have to compare the various vendors item by item. for instance i have found mars will be lower compared to P&C on some items, but higher on others.
as to service i may be wrong but i believe i have read here and elsewhere that P&C has made errors when fulfilling orders, though they quickly make right any mistakes which are their fault.
my own experience with P&C, Mars, and 4Noggins they ARE SUPERB when it comes to customer service, selection and communication; if forced to select one and price is your determinant then just you won't go wrong in selecting the cheapest FOR A SPECIFIC ITEM. jrtaster/john