Is the 50 dollars for labor payment to someone else?
If it was really 28/hr, it would have not been that bad considering you are new. You left out the gas and wear and tear on your truck. Not to mention to myriad of other small expenses it cost to be legit and keep the lights on.
Most guys charge a fee for getting the material, and you should be able to mark the material up slightly.
500-550 would be what most guys would shoot for while trying to lower the hours worked. This way you can cover the standard cost of doing business while keeping a few dollars in your pocket.