I'm trying to resolve poor compass interference, possibly due to using the pixhawk internal compass rather than external. Currently getting bad readings outside of limits and toilet bowl in loiter mode. The GPS module that came with it I think is quite basic and may need upgrading.

• Compass Offset of 'X' was at 225 (I read over -150 to +150 is bad)
• Also mag vs throttle reading jumped to about 50% - Anything over 30% is bad)

So my question is about quality. So many GPS with compass modules on offer on eBay at very different prices. I don't really know what I'm buying here!

For example:

http://tinyurl.com/q43korm

UBLOX GPS CHIP & COMPASS NEO M8N MODULE

£59.99

And much cheaper....

http://tinyurl.com/p5tz5wc

NEO-7N Flight Controller GPS Module with 3 Axis Compass

£19.99

Both state they have GPS and compass. Can anyone offer an opinion on selecting one. Why pay for the more expensive one?!

Thanks :)