In probably 300+ transactions between here and Facebook, exactly 1 person has sent me cash. It got lost in the mail (maybe he lied to me and never sent it, maybe a postal worker stole it, I have no idea). I know that it was a Protostar or something pretty inexpensive and if I recall correctly, I just sent it to him anyway. I also know that the next time a person asks me if I accept cash, I will kindly decline, and I know that I will never send cash myself.
I suggest talking with your father and trying to find an amicable solution where he allows you to spend some of your own money on a hobby you enjoy, and helps you set up a PayPal account so that you can feel safe when you buy or sell.