Someone asked me the other day which handbag organizer I like the best.
My favorite is the VIP, though I do have several Inpaq organizers in different sizes.
You put them inside your handbag and as you change handbags you just lift the liner (as they are sometimes called) out and put them into your new bag. They can also be used to keep your Filofax and stationery together.
And of course if you do an eBay search for handbag organizer you will get lots of hits, as can be seen when I did a search for a purple one here. As you can see, you can find them for as little as £1 with free postage. Quality varies and many of them do not have padded bottoms but if you are not sure if you would get on with a handbag liner/organiser, it is nice to start with a cheapie to use on a trial run.