I've got several of these . I need to pare things down a bit because I'm not using all of them. While APM2.0 is convenient and compact for many applications it is not optimal for installs where you need a remote magnetometer and GPS. Of course these have the ATMega2560 processor at 16mhz, 3 axis gyros, 3 axis accelerometers, barometric altimeter, etc. etc. just like the APM2.0 Plus the APM1.0 it has quite a few other features not found on the APM2.0. Reality is, if you have the space, APM1.0 is the more powerful unit. Perfect for fixed wing, bi-copters (traditional helicopters), and mid to large multicopters. These work great on smaller quads as well but the APM2.0 is probably a better choice unless you need remote magnetometer/GPS.
Anyhow, I'm offering two of them right now. Both are ready to go 2560 units and both come with new external MediaTek GPS the used APM1.0 also comes with an installed HMC5883L. Note: The new unit does not come with the HMC5883L shown in the photo - I've decided to keep that. DIYDrones is charging $299 for the same exact thing pluse another $40+ for the magnetometer. I'm asking $220 shipped for the used unit (with GPS AND mag!) it has had the switch replaced on it - even though the software no longer uses it (first photo) and $225 shipped for the new, unflown APM1.0 (with GPS but no mag) (second photo).
Prices are shipped CONUS only others will be charged a bit extra to cover the additional costs.