A really big builder, or service company, may be eligible for some rebates, but I have never been one of those, so I don't know. Some are large enough to buy manufacturer-direct and get the prices my suppliers get, which is usually about a 3% discount (wholesale suppliers work on a very slim margin).
Prices online for pool related items is, many times, at or lower than my cost through distribution and it affects pool stores as well. Many online retailers don't actually have inventory, nor the overhead, but drop ship from the manufacturer. That's one reason all, or most, of the manufacturers are trying to limit online sales with restrictions on warranties, etc. to protect their "brick and mortar" companies' businesses (and ones like me, though I don't care). Improper installations that result in "warranty" claims are another reason ("Of course I installed it right!")