My local stationary store went belly up and There's no place within a reasonable distance where I can get shipping boxes. Is there a decent place online that I can get them? Looking for sizes around 48x6x4 or so.
Try your local gunshop.. they get tons of boxes and are just waiting for people to take them off their hands. Another option is a music store.. keyboards and guitar/bass take about the same size boxes.
Go to the UPS website and setup a free online shipper account.
Then order free shipping supplies.
For long guns, I use two of the Large Express Boxes, overlapping and taping them together.
You don't have to ship express just because the box is labeled that way. I use them all the time for ground shipments. Driver confirmed that the barcode scanners don't care what the box looks like.
They Triangle shaped tubes work great if you're shipping a shotgun or rifle with no attached optics.
I'll break down the firearm and tape two of them together sometimes.
The Express boxes make damned nice target backstops too.
Try the local furniture store. You wouldn't believe the size of the box a couch or wardrobe comes shipped in. A little creative blade work and some tape, and voila- one custom sized box.
Uline.com is very expensive IMHO. I'm asssuming you are looking for something over a hardcase? If you are shipping a whole rifle, sorry - you MUST use a hard case (OK to box over it) - any mail service, Fedex, UPS, USPS - will all tear a rifle box apart. I have been amazed at what FedEx can do to a Starlight or Pelican...