Low cost modules for experimenters

My Facebook memories for today showed the low cost 70cm AM modules that you can buy on eBay. Others have used the HB100 10 GHz Doppler radar modules. Others have used 5.6GHz modules for TV. I am sure there are others. 

Since my 2013 stroke, I have been unable to do much building work. For serious experimenters there is a lot of choice.

These modules could form the heart of many projects and are well worth a look.