Hi,
on my 1984 diesel 300 series, my brakes are not working at low speeds like parallel parking, driving around the grocery lot and stopping where they should at red lights. The engine keeps running when the key is removed, and the transmission shifts hard at low speeds. A friend told me to check the vacuum lines. I know nothing about cars. I took the car to a mechanic, he performed a smoke test, no leaks. He checked the pressure produced by the vacuum pump, and reported it was lower than the minimum required. Hence the car needs a new pump. The mechanic reported this fix to cost about $800.
I am a college student, and never had anyone teach me about car repair. My friend informs me that if I had the piece re-built and did the repair myself it would cost me about $300. That is a big difference, and I would not have to sell the car and be car-less. But if I do not learn how to do repairs I will not keep the car, it would be too expensive to take it to a mechanic every time.

My questions to you'll, is 1) based on the information I gave, would you concur with the mechanic that the car needs a new vacuum pump? 2) being of average intelligence, no mechanical background, no knowledge of tools, basically a blank state; what are the chances that individual could self-teach and correctly make a major repair?

Any other advice would be greatly appreciated: is this the right forum for me? if I sell the car, how should I calculate my asking price, (I've owned the car since May, 150,000 miles b/c the engine was replaced by a previous owner, A/C and heat work, really the car runs well, i'm kinda starting to like it, but as a college student I lack the time and money if its going to need work constantly, since owning it from May I put about $600 from mechanic visits, compared to about $100 would have been if I knew how to do the repairs myself.)....and anything else. really all the concise info you can give me.

Thank you