Big Box Vs Plumbing Supply . The only way to compare is to look at the number under the bar code or the exact model number. Workers at big box stores often have a general knowledge of plumbing, but it’s not even close to what workers at the plumbing supply shop have. How To Use Comstar Hot Power Drain Cleaner pandafemininablogue from pandafemininablogue.blogspot.com The contractor and plumber stated the reason the products were cheaper was that parts inside the fixtures were cheap plastic while the plumbing supply store was made of metal. Typical differences between box store and professional grade plumbing supplies. Look for a toilet in the $125.00 price range when looking at box stores,just say no to those $50 toilet in a box kits unless it comes with a good free plunger.