I use three different brands of markers, Touch, Prismacolor and Copic, and have been successful in refilling them all. At first I didn't see the value in refilling, but after I counted up the number of markers hanging around the studio it made economic sense.....and especially after I ran out of marker juice during a demonstration.
Prismacolor markers can also be refilled either by slowly dripping the toner onto the tip or by drilling a small hole down next to the tip (there is a groove) and using the needle on the refill container. Dripping seems easier.
In my opinion these are the ups and downs of the different brands: Prismacolor: easy to find, the tip has three edges for differing lines, but they have a tendency to roll and the caps are hard to get off. Touch: seem to hold a lot of ink, not as easy to find. Copic: replaceable tips, different size markers with larger tips, easy to pop tips in and out, seem to be less 'toxic' smelling, harder to find, expensive. Copics refill easily and have differing sizes. I've been using their extra wide 1" for some of my block-in. The more I use Copic Markers the more I like them.
There are many good sources for markers. Dick Blick has a nice assortment. Marker Pop, however, has become my current online source as they have very reasonable shipping and a good inventory. Locally I get them at Daniel Smith, Seattle store or the Artist's Edge in Poulsbo.