I have a MInelab GP3500 with the stock coil, new Doc's Goldscreamer signal enhancer and coiltek lithium Ion battery set up with 2 new battery's as well as the stock lead acid 6 volt battery. I only hunt in bad soil once or twice a year so am wondering if I may be better off selling this and trying a different unit. Any idea on the value of my GP3500? I have the control box cover as well as the padded arm rest also. I have seen some guys pull some good stuff out deep with these units.