The price is fixed. They don’t do finance. The drawback is they ask for top book price and unless things have changed they don’t offer any warranty etc.
From my research the best option is to find which garage has bought the car or which auction it is going through. If you buy it from that garage then by law you are protected if something goes wrong. You can even buy a warranty from the said garage and pay by finance. If through auction you might get the car cheaper. It’s a matter of whether you can find out where the car is going after you return it.
When I returned mine I asked for price just out of curiousity. After returning it I found it advertised at a local franchise dealer at a slightly lower price but with some warranty etc.