Tinpilot
Remember we are still waiting for the infamous sub-£500 Mode S the size of a mobile phone and with long-lasting batteries.
If you think we'll get a $200 ADS-B, you'll be waiting a long time. The CAA with its noted antipathy to GPS won't allow a Garmin 196 or SkymapIII to be the driving GPS either.
It will be a high-end certified model - and energy-hungry- so we'll be even less likely to have one in microlights or gliders