I am running 2 Garmins simultaneously on my bikes now (my cousin donated an Edge 500, which I use for ride stats; @Sharky donated an Edge 200, which I use for navigation). That means that I need a lot of mounts. I used up the ones I had and then bought some extras on Amazon and eBay.
I like these, which are handy if you have at least one spacer above your stem...
I picked that up for a couple of pounds on Amazon. That particular merchant seems to have stopped selling now but if you shop around you can still find them for under £3.
Here it is mounted on one of my bikes, together with an out-front mount which I found cheap on eBay direct from China (it took over a month to arrive!).
I bought a used suntour gpx rear derailleur for the benotto frame I am building(see my avatar)
Slowly getting the bits and pieces for the rebuild via ebay and hoping next year to have the project on the road