What I've learned over the last few weeks of looking at secondhand and antique stores, is that I can either find nice glass inkwells with lids for upwards of $50, or I can find them for $20 or less, but with no lids! I was seeing the same thing at the flea market. A whole lot of frustration.
At the end of the day, I took one trip around the parking lot (this flea market is indoors, but there are vendors who set up in the lot). In one corner, I found this:

It's not an inkwell. At least, that's not what it was made for, but it will work very nicely. It's milk glass, with no chips or cracks and no discoloration. The lid is steel, and is quite rusty, but it doesn't leak. I tested it by filling with water and a drop of food coloring, and letting it sit on its side for a day on paper towels. Not a drop. Best of all, it cost me $2!
Chalk one up for the good guys!
If I get ambitious, I'll use a Dremel brushwheel on the lid to clean off the rust and then spray-paint it a nice fun color.