For sale is a Lee Bench plate for $15 shipped. It will not fit in a small flat rate box and it will probably cost a good part of the $15 to ship it.
The idea behind this device is to mount it to your bench and then attach presses, etc. temporarily. In my opinion, it's best use is for light duty things like mounting a case trimmer and I did use it a little for that; now that I have a larger bench, I don't need it.
Accept for payment are personal checks and U. S. Postal Service money orders. I don't accept PayPal.