What do you feel is fair to charge

Last year had a friend ask me to care for a few animals out of their collection. Was supposed to be 20-25 animals . I agreed they were going through major life issues and they said breed them split the clutch. We go to pick these up and they are having big issues and look at me tell me to take the whole collection and do this with as they are going to die otherwise. Me and my girlfriend didn't really want to but many of these snakes had no water etc bad space. We had the extra room so we did it to help the friend and the snake. Otherwise we were worried they all would die. "they are separated from our collection completely. Well instead of 20-25 it was 140 adults plus some hold backs etc.
Most were in bad shape dehydrated and underfed . "Some died within the first couple weeks " We have held these taking care of them feeding cleaning etc for 8 months . Most are just now back to what I consider healthy weights. Not even breeder ready weights .
Now they decided they need money and are planning to sell all the animals .
In this 8 months I have been buying or breeding all the rodents and bedding etc. No money has been given for the care of these animals .
What do you think I should charge them for this . As I have spent Thousands out of pocket to nurse their animals back to health and they act like I shouldn't get anything.One in common friend said to pull out a few animals and say these are payment etc.Another feels I should invoice them for rodents,bedding.

What do you all feel would be the right thing to do?