I've just bought an Android tablet. Cost me £100 for an 8" screen, somewhat smaller than an iPad, though I saw 9" ones (same size as iPad) from about £150 new.

These cheaper Android tablets have perfectly adequate displays. They may lack some of the bells and whistles of an iPad, but if what you are after is mainly to display your music, they will do just fine.

I have put my songs in as well as my tune books in pdf format and the display is a reasonable size, though a 9" one would be closer to what you get from an A4 sheet. You can also get 10" Android tablets. They have a 16:9 screen aspect ratio where a 9" one has a 4:3 aspect ratio. I prefer the 4:3 aspect ratio which is why I went for a 8" tablet as it was a good compromise between screen size and size to carry round. I'm just waiting for my daughter to make me a holder for it before I can replace my books when I go out.