U-Haul sells a nice, thick "27" TV Box" that should fit the 4x10 cab pretty well.
1. Wrap the cabinet in cardboard at least two times (two boxes thick) and then wrap it with bubble wrap.
2. Fill the bottom of the U-haul box with about three inches deep of pinched-apart styrofoam (like the kind from computer boxes). Pinch it apart into one-to-two inch pieces and chunks.
3. Glue together corner pieces of styrofoam for the cabinet.
4. Set the cardboard wrapped cabinet into the U-haul box, putting the corner pieces in the bottom.
5. Fill the remaining voids around the cabinet with the pinched apart styrofoam pieces and chunks, making sure it is tight. In fact, the walls of the U-haul box can bulge a bit.
6. Tape the box closed extremely well. Use a whole roll of tape! Get some of the string-reinforced tape as well to wrap around the sides and around the top one time. Make sure to tape all joints too.
Should cost about $75-95 depending on final weight and dimensions via FedEx Ground/Home delivery.