It can be worth negotiating. The "to buy" price was set at the outset of the agreement, and markets are different now. Under some types of finance agreement, the sale has to be to a 3rd party, historically because of capital relief rules.
It used to be possible to get a mate, sorry, I mean an independant third party, to make an offer to buy the vehicle. They might just happen to sell it right back to you. The finance company is no longer involved at that stage.
Cheers
Mike