Toyota Repair: dashboard lights come on, toyota corola, alternator problem

Question
i have a 1991 toyota corola.  the alt. and the light burned out light on the dashboard both come on once and a while.  when that happens, my btake lights don't work.  at first there seemed no reason why it happens.  right before the problems started my right brake light burned out. i replaced yhe bulb. the next problem started happening with in 30 minutes of the first.  at first the problem seemed to be related to driving over bumps.  i thought there might be a problem with the wiring.  i really didn' find anything.  then i notived one morning when i was frustrated by the light problem, i revved the engin and the waring lights went off and the brake lights worked.  now i rev the engin when the problem comes up.  that seem to be a solution that is not as effictive as it used to be. i looked on the internet and found one site that implied that the alternator might be the problem.  the question was about a problem some one had after steam cleaning the engine.  so, does this problem sound like an alternator problem?  how do i test the alternator?  i have seen alternators prived all over the place.  from about $50 to over $200.  what is the diferance?  is it hard replace the alternator.  it is a 1991 toyota, so i don'twant to spend up too much money on it if possible.  thank you for your help in advance.  

Answer
could  be alternator or a short ? this is a tough question cause i am not there to actually see the problem occur. bring the vehicle to a dealer and have them do an alternor and charging test. let me know. the differance in alternators is better quality, try to always go with the original type.