Another ownership question

I've searched through the archives, and there is a lot of useful information
there concerning buying and affording an airplane. My question,
specifically, is this: If I bought a 1977-ish Cessna 172 that is IFR
equipped with a low time engine for, say, around $45,000, can I beat the
rental cost ($77/hr) over the course of a year flying 150-200 hrs a year?
(The purchase price is based on looking through aso.com at $50K asking
price- surely the asking price is not going to be the selling price?)

The answer my research in r.a.o seems to yield is "maybe", and anything less
than 150 hrs would be "no". I fly for enjoyment, and even though I am a
woman I don't mind tinkering around with things; an airplane would obviously
involve a lot of tinkering

TIA-

Wendy