We base our price on:
1) our original cost

2) tech time to test and update each unit

3) free insured shipping (these are heavy and expensive to provide insurance)

4) condition of the product (used in manufacturer's box with all accessories)

5) comparable prices

6) Current product availability, and 

7) the 13.5% fee ebay takes from each sale. 

Therefore, only very reasonable best offers can be considered.