If it's a bowl that you've got, you could do what I did, especially if you have a heater or filter power cord coming out. I have a heater power cord coming out of my little betta bowl, so I cut a circle of plastic canvas that is about an inch wider in diameter than the opening of the bowl, then I cut a small hole for the cord. The lid 'snaps' around the cord, which holds it in place and there's plenty of space for air to get in for the betta to breath since the plastic canvas is just a bunch of holes. If you want a pic of what I did, I can take one tonight and post it. Another thing I've thought of is, if you have any sewing talent at all, and if you don't have any cords in your tank, take some netting material, cut a large circle from it. Sew a casing around the edge and run some thin elastic inside that is narrower than the opening of the bowl. That should be easy to put around the rim of the bowl, it will keep the betta inside, but still allow air movement.
The idea of all glass lids bothers me, because it seems like if there isn't a lot of openings available, the betta would potentially suffocate since not much fresh air would be able to get in.