Where to find lantern glass panel replacements?

I actually have the same problems

Drusilla Imports

Any glass shop will cut them for you and they are cheap. Bring the old one or measurements

Used to have same problem at old house. Take out one of the unbroken glass panels And take it to capital glass. Cost $5-$10 and they'll cut a new one for you. We went ahead and got them to cut 5-6 the last time since it seemed every time a major storm came through one of the panels got broken. The tornado last February destroyed the lanterns so we did end up getting new ones for that.

I've taken a good piece to an ACE hardware and had them cut one to match. Only took a few minutes and was pretty inexpensive.

WOW

is this the natural gas type? I need the little ceramic mantle holders for mine.

We typically do tempered glass in gas lamps and annealed in electrical lamps. The tempered will eventually de-temper due to the heat from the flame, but it buys you some time before a storm blows it out.

Glass is priced by rounding up to the next even inch. 3 sq. ft. minimum is typical.
Typical annealed lantern piece = $15
Typical tempered lantern piece = $18