Your paying for shipping no matter what, shop pays it then it gets added to the price BUT the axle alone without hubs ships FedEx or UPS (under weight
limit) with the hubs on it goes over their weight
limit and has to be shipped common carrier. Shop probably can order bare axle, and has hubs in quantity so shop might save you a little something on shipping.
MN is in a zone that tends to be pretty expensive for shipping but ordering from Scamp
does eliminate the shop labor expense of measuring and push job into a simpler remove and replace welding operation. Wonder if scamp would fax order into axle company with your address for delivery, could make for cheaper shipping. You pay Scamp but the axle is shipped to your house or the shop. Makes no sense to pay shipping to Scamp in Minn. and then shipping to your location.
I would not go with "half decent" welder but this is not brain surgery either, if one is able to set the axle true to the center line of trailer frame, which is basically a measuring operation that has been around since the ancient Egyptians. And has the welding skills to build and repair trailers they should be acceptable.
One thing that might help is to show the shops pictures of the axle mount. Then if you can say to the shop you ordered the axle from or through the manufacturer what would they charge to remove this one in the picture and weld the same new one on. Known situation for remove and replace is better question to present than "replace axle on an old RV" because RV manufacturers have a lot more variation in design than a normal utility trailer. Lot more unknowns and potential complications that the shop might want to avoid.
I go back to something I mentioned earlier, portable welding services. Those tend to be welders with fairly high skill level (harder to work in the field than in a shop) and if you show them the picture of axle to be removed and have the new axle they may well take the job. May charge a bit more per hour but you do avoid the transport cost/hassle.
Small tip on taking the axle bracket picture go from both sides, and bottom. Zoom in some but leave yourself room for cropping to straighten the picture and cropping will zoom in on the detail. Might want to put shop light
or two under trailer to avoid tendency of flash to wash out detail at close range.
Once you get through this unfortunate mess you will have an axle good for 10 - 20 years. If you keep the trailer that gives you value, if you sell the camper it has value. Big hassle now but it does have an upside on the other side.