I can see now why so many new business's fail within the first few years.... people really have no clue.
You can't make a living selling $2 parts. As far as heavy items, guess what, they will charge the dealer just as much to get it to his door as they will you to get it to yours.
A 25-30% markup doesn't cut it unless you are doing huge volume. When you figure the costs of shipping, rent, insurance, advertising, utilities, employees if you have any, the FFL, credit card proccessing, security system, Inventory taxes, local licenses, and others(I could go on for a long time) that 25-30% evaporates real quickly.
Don't worry though, go ahead and buy from Shotgun News and the internet and tell the local guys to go to hell. Sooner or later they will deciede that its easier to make a living elsewhere, and when you find that $500 pre-ban online but can't find an FFL within 150 miles to do a transfer you will only have yourself to blame. When you need a new scope mount for the opening day of deer season the next day, or a loved one needs a personal protection gun in a hurry, or you need a part to make the shoot the next day, rest well knowing that while it may take you a week to get it, at least no greedy capitalist made a profit on you