I wish the author would have tried negotiating with the pawn shop. The pawn shop would have been out the entire 225 had she not bought the laptop back. Realizing this she could have offered a lot less and it would have still been in their best interest to sell it to her. She just needed to bluff a bit that she would be willing to let the police confiscate it if the cost was going to be over X. I bet she could have gotten it back for $50.
Also as others mentioned it's a pretty broken system that she would need to do this at all - that her laptop would be locked up in evidence for so long. But lemonade from lemons, ect...
EDIT: Also do we even have any proof that the pawn shop actually paid 225 for the laptop? It's in their best interest (financially, not morally) to lie and state a higher price. Ie. They may have profited off of selling the laptop back to her.