re: Inexpensive, home-made screen protector
That will work, but if you have to replace it, it might be hard getting the adhesive off the screen. I suspect most solvents would cloud the plastic or worse.
Most electronics or office stores sell, very cheaply, little sheets of that plastic they use to make window stickers for cars. Cut it to size, and bingo.
Of course, a lot of small electronics come packed with a little clear plastic sheet already on their screens (it's not always obvious--look closely). I still have that on my current cell phone.