Its not all the same......
SUPPOSEDLY (don't quote me ont this) there are different qualities of ingredients that go into all these. Before there was a Lesco in my area, I bought the Scotts 4 step program off of a golf course maintenance supplier and the prices weren't really that bad unless you compared them to like "K-gro" the K-Mart label or something along those lines. I guess they just built their trust in a market and people will pay for that. I never had problems with it, and my customers never had a problem paying for the results, so I stuck with a good thing.
I look at it like this. We ***** when customers of ours price shop on us, and would drop us if they could save $5 a month. How much of a hypocrit would I be if I did the same when buying from a supplier or parts store, etc.
My parts store was much higher priced then the larger ones around, but they always took great care of me, I had a 24 hour response number, I always got loaner equipment if mine needed to go into the shop for more than a day, etc. The extra money was well worth the benefits.