you can buy new lock sets with glass knobs. I have one on my guest bathroom. It locks.
Go on-line and google 'old lock sets' or some such wording and find some of the people who sell old sets and repair them directly. They will be able to tell you exactly what the problems are, and the solutions.

You should also post at the old house sites, as well as here.

No, you shouldn't just get over it!

Neesie,
It looks like your eBay seller also offers new lock sets to go with her glass knobs -- have you emailed her about it?

Here is a link that might be useful: extra locks for glass knob sets

I don't know anything about this vendor, Neesie, but they have locking 'privacy' glass knobsets.

Here is a link that might be useful: Looking in the Attic

Renovators Supply has locks designed for use with separate knobs.
The shaft sizes and threads have been 'standard' for a long time.

There are also other eBay vendors who sell retrofitted privacy locks to use with any antique knobs, see link. Good luck and remember: pictures, pictures when it's done! ;-)

Here is a link that might be useful: retrofitted privacy locks for glass knobs