What, do you mean those vinyl covered sets, with pairs of 3, 5, and 8-pounders, so she can 'just tone up her jiggly parts'? Are you new here?
Powerblocks will be the best bet. You should be able to find a pair of the Personal set (goes from 5-45 pounds) for around $200. There's an add-on kit that can bring it as heavy as 65 pounds, but that's it.
Their Pro set is around $250, if I remember, starts from 5-45 also, but has 2 2.5-pound adjustable inserts, so you can go in more precise increments. Also, the Pro can have an add-on to go up to 85, or 125-pounds. Powerblocks are definitely the tops, in terms of adjustable DBs.
The Bowflex ones are literally made of plastic, and don't feel sturdy. Powerblacks take a little getting used to the square, caged-feeling, but they're awesome.
There are actually a handfull of exercises you can do with them, that you can't do with "regular" DBs, like bear walks and renegade rows.
What makes you think she'd stop using them? Sounds like someone needs to learn a lesson or two from our T-Vixens.