These are Bliss' (Ellen Page) Barbie skates that she can be seen wearing during her tryout to get on one of the local Roller Derby teams in the movie Whip It. The 'Barbie' portion of the skates appears to be production made with stickers applied to a pair of skates with pink wheels. Little pen-scribbles where then drawn all over the stickers, which can be matched onscreen to the pair of skates Bliss wears during the tryouts. The inside of the skates are also both marked 'Ellen'.

Here's a couple of production photos taken during shooting that show Ellen Page using these skates:
(The various markings on the Barbie stickers match up perfectly in these shots. There is another pair of
Barbie skates that match up with shots of Bliss skating on the street in her neighborhood.)

Close-up of the skate she's holding:

Putting them on before the try-outs: