Do be careful of what you use.
Prefab cabinets from big box stores are nearly always made from particle board.
Aside from the weight issue, these cabinets are totally unsuitable for anything that moves down the road. They will break apart and wind up in pile of firewood on the floor. They are designed for in place use only, not moving.
RV cabinets are made from small dimensional lumber, and paneling or luan glued and stapled to it. They are much stronger and will withstand the bouncing around and flexing as you travel down the road.
They are very easy to fabricate, except the doors take a little more effort. But the cabinet boxes are amazingly simple. A small tablesaw, some KD spruce and off the shelf 1/8" paneling, wood glue and an 18 or 20 ga stapler and you're in business.