A lot of those "oem" parts are generic parts and used on many different trailers. For example the vent lid at Roberts are $22.00, the ones at Crossroads RV, down the street are $19.
The amber marker light I just replaced for $3.00 from Roberts, I found a few days later down the street for the exact same price.
I may be lucky; not sure.
But they do great work in setting up a trailer. They did the 4.5 inch lift, addition of extra batteries, tires, etc., on my popup all via requests over the phone.
Before moving here, I had referred a lot of people to Roberts for parts too. One thing, you can't go wrong with them; they stand behind it all.
Trailer: Lifted 228BH, heavy duty springs and Yokohama tires
TV: 2016 GMC Sierra Z71 4x4 CC, SLT
Spare TV: Two Alaskan Malamutes
Living somewhere in ID; previously lived in Moab UT; previous to that, don't ask!