After seeing the builds of Drsues and FissionBomb, I realised I had an old Syma X11c toy-quad as well as an Eachine TX03 FPV camera/VTx, neither of them being used. So, here what you get when you combine the two and remove some stuff from the SYMA X11c.

Build
I first desoldered the camera (power/ground/data cables) that is normally onboard the X11c (mine wasn't working properly anyway after some snowy landings). Then I soldered a Losi Micro T-connector on to the battery pads to power the camera, making sure I got the polarities right.

To get the weight down, I removed the prop guards, the bottom half of the frame as well as the LEDs (they actually add 0.4 g to the quad...). In total, I removed 7.1 grams worth of stuff whereas the TX03 weighs about 6 g so the build is actually lighter than before.

However, since the battery now powers both camera and quad, the flight time is less than 4 min and it is a little worse than before if a light breeze comes around. In any case, it would probably be a fun and cheap "build" to get into FPV with.

Summary
Nice and easy modifications gave a pretty okay quad to use for beginners in FPV flying. It flies fine indoors but if you take it outdoors, even the smallest breeze will give you big trouble.

Again, thanks to Drsues and FissionBomb for this great idea!