Financial talk

My husbands family (so my in laws) are having a get together this weekend. It is at a camp ground over an hour away. We have no money to attend. Some family members have offered to help out. By the time we gas up and pay the entrance fee it will be between $70 and $100. I do not feel right about them paying our way. Especialy since that is how much we spend on diapers every month. I am having a hard time reconciling this. I feel like that is a lot of money to drive an hour, hang out for a few hours and go home. Plus I have a 3 year old and an infant. The baby is too young for bug spray... I want to see everyone but... what I've already said. My husband is mad about it though. I told him he could go. He said the famiy wanted to see the girls... I just don't know what is the right thing to do here. His parents are already taking us to the zoo in the next few weeks...