Don't expect others to have the same degree of thoughfulness as yourself. Buy your son a new rc toy and tell your neighbor it's not a problem. No point in losing a good relationship with a neighbor over a $100 toy.
As mentioned above rc toys should not be on the street but it is a risk you want to take so you take your chances...
Also if you had run over somebody else's rc toy you likely would have paid for it but don't expect others to behave like you.
G.