Re: 3DR Solo
Having just DIY'd a quadcopter of roughly the same size, here are some rough maths...
Frame kit: $100
Flight controller (Naze 32): $40
Camera gimbal: $120
Radio transmitter, reciever, and GoPro not included... a DIY kit comes in at around $500'ish, with shipping, etc. So, $1000 for an almost ready to fly kit, really is not that bad... and the flight controller in my kit is not nearly as sophisticated (or expensive) as the pixhawk. The naze 32 is more than enough for simply flying a go-pro-gimbal around. If you want autonomous mapping, yeah, the pixhawk is great... but also $200. Apples to apples, you save about $350 building it yourself.
TL;DR, 3DR drone is good deal if you don't like building these things yourself.