Horizon Flyer - noted re the cost and features of a new Apple devices vs. Android, but eBay is awash with 'old' iPads that cope perfectly well with SD; the graphics and processors aren't comparable by today's standards, but perfectly adequate for flying. Which is exactly what I use mine for - it lives in the aircraft.
Obviously you're correct, but it is worth pointing out that I paid £80 for a re-furbished Samsung Galaxy Tab 4 (8"), and didn't need an external GPS device. All I needed was a yoke mount (from ram mount - they really are good).
The screen is a bit slow to refresh when in planning mode (but for the most part I use my PC for that anyway, and save the route to the cloud ready to open on my tablet). In the plane it works perfectly.