Advice on this please need a good lie to get outta this..?

so i'm an au pair in france. I came back to the US to get my visa after being there for 3 months.I was told i had to be back in france by my french family before july 7th becuase they leave for morrooco for a month or else i can't return until august. Problem is a can't get the money for a plane ticket so quickly, i don't want to tell them that i can't get the money..also as awesome as morocco is i'm sure i don't want to go just yet. nervous about meeting more family members and such.long story. Is there something i can say to get out of this maybe? A good lie that seems possible or true maybe?