We are getting a lot of questions about Lease/option;
Some people think that there are a lot of L/O properties out there,
There are not!
The primary reason for the Buyer doing this, is that they cannot get a loan from a bank.
The primary reason for the Seller doing this, is that they haven't been able to sell their property.
To answer your questions:
There are not very many properties for $75,000 that do not need a lot of re-hab,
Most of them are owned by the Banks.
Assuming that you did find a viable house for $75, the terms for a L/O are variable; they can be whatever the two principles agree to, including the Deposit, the monthly payment, the allocation to the Option, the Selling price and the Contingencies and terms.
This is a real "Caviat Emptor" for all concerned:
I would suggest involving a Real Estate Attorney.
Good luck and may God bless