Lead dog quotes for around a grand for his. No sliders included. Not bad, but I was hoping to have a usable top box as well. I currently have a small box that includes my battery and controller. If I don’t have a place for that in the built box then I’ll have to take the spare from the tongue and relocate.
I had a custom box built by American Truck Box and then made my own slide for a fridge. It was about $1200 when all was said and done and that's with me doing the slide. I had mine made out of aluminum which has gone up in price so who knows what it would cost now.