cargo lining insulation ....

I've read some of the other threads and as one person has said, insulating seems like opening a can of worms with all the different methods. I just bought the 350 high roof. I race dogsleds and xc ski so I plan on using it during the winter to haul the dogs and equipment. I plan to sleep in it too with a cot for now and eventually build a fold down bed of some sort. I plan on building a workbench to do various things and also to wax ski's. I've price the liners and can get the liner for about $800 because I would like it to look nice and not all ghetto. I thought about just buying the material and cutting to fit and use the plastic snaps, but I wouldn't even know where to buy stock plastic lining. I'll be heating it with a propane portable buddy. What would the best insulation be for my cold weather purposes. I will also use to camp out during summer to go to bike races and mt. biking throughout the midwest. I thought about getting the ceiling liner too, but that's an extra $500 and thought that could wait. I appreciate any info, thanks.