For the cabinets, you can save weight, money, and build a more durable cabinet by doing it yourself.
For ceiling panels, the most inexpensive is probably going to be Luan or other species plywood and paint them before installation. An alternative might be FRP plastic but you will fight getting them to layup on the ceiling without a wrinkle or bow. The nice thing about FRP is that the stuff is basically indestructible and can be washed with soap and water. 1/4" plywood is about $15/sheet and FRP is about $20/sheet in the big box stores in Minnesota. YMMV.
DIY cabinet:

