My CCW purse (although it's used much more as just a regular purse I love it so much) is from Gun Tote'n Mamas.
http://www.guntotenmamas.com/
Their average price is somewhere around $100-125. Lots of variety of purses. Their prices seem to be the most reasonable I've seen. The Coronado bags sold at Cabelas are nice, but not my style, and the prices are $250 and up (going from memory).
The GTM purses I've seen all have dedicated gun compartments with holsters that attach with velcro, so you can position them as needed.
I have
this one. It can handle up to a full size (my M&P 9, for example). It's gotten good reviews from folks such as Kathy Jackson (the Cornered Cat website and book) as being the easiest/quickest to draw from. It doesn't hold a lot of stuff, though, so if your mom hauls around a purse you could also hide a dog or a newborn baby in, she would not be happy with this purse. I carry a minimal amount of stuff with me, so this works.
I also have
this purse from the same company, but the gun compartment in back is too small. My Shield doesn't fit so I can easily draw and quickly. I had to use the holster from my other purse in it. My Ruger LCR also wouldn't fit decently it in. Must be made for the really small semi-autos (LCP and such).
Suggestions: make sure your mom understands she can't leave her purse ANYWHERE. When out to eat, she needs to keep the bag around her, or between her feet. Just slinging it over the back of the restaurant chair isn't kosher. Getting one she can wear cross-body is best. The GTM bags have slash proof straps.
This
book has a chapter on gun purses (as well as chapters on all sorts of different ways to carry). I'd suggest you get it for your mom. The women pictured in the book aren't cute 20-somethings, but women of all ages and body types, including a good many middle-aged or older ones.
The Cornered Cat book from Kathy Jackson (
here) would also be a good book for your mom. I recommend/give both away frequently.
Once your mom settles on a purse, please make sure she practices drawing from it a lot (unloaded pistol, of course).
ETA: before I got my CCL, I thought I would purse carry. I discovered I can carry on body, so that's what I do most of the time (appendix).