I don't think anyone is giving you crap for spending your money as you see fit. What they may give you crap about is expecting a $300 part to have the same level of fit and finish as a $600+ part using the same materials and to be of the same level of quality.
I'm not saying what you have is no good and I'm not saying every expensive item better than the cheap ones but it is true more often than not that you get what you pay.
If you like the exhaust note of this piece I'd say you got a great deal @ $299 but to expect it to fit to exacting tolerances down to the micron is asking a lot for a $299 part.
EDIT: the fitment issue you where initially concerned about anyway where so minor that 99% of people on earf wouldn't have noticed one bit.