OT - Where to get Glass for coffee tables

[Pterodactyl]

I have a friend who just bought some new coffee tables for her house and is looking for glass, acrylic or plexiglass to put on top. All 3 tables are not flat but have an inset that would be perfect for a glass top. We have priced out options at Lowe's but it is pretty expensive.
Does anybody know where we could get either glass, plexiglass or acrylic at a reasonable price?

Here are the dimensions that she needs:
1 piece 33 3/8 x 33 3/8
2 pieces 25 3/8 x 18 1/2

Any suggestions would be greatly appreciated.
Thanks.