Well, look at the "ballast" kits they sell. Okay, great those are marked up also. To buy everything you'd need, bulb, reflector, cords and ballast kit, comes out to their price on the actual light unit itself.
THIS tells me (as a online store business owner myself) that they still sell everything just under MSRP. What they do, is they price everything (individually) at retail, add it up and that's the total price. Parts for their light kit with reflector, bulbs, etc. are priced retail individually. So yes, they are making a GOOD profit for their "OWN brand" products. All they will do essentially is house a ballast kit and add a bulb and reflector and make the same amount of money as they would normally.
The only difference is that they may sell non "own brand" slightly below MSRP to make up prices in volume.
BTW, "Own Brand" is a term we use in the business as products you make or put together as your own and sell it for equivalent pricing.