A balance is about $10 per wheel. An Alignment is between $26 and $70 for all 4 wheels.
If you have old mags, they could also be slightly buckled (which is very common, and nothing to worry about). If this is the case, a balance should minimise any vibration but it might not get rid of of the vibration completely.
If its a 99 camry, I wouldnt expect this to be the case, unless the wife has hit something at speed (also could be very common)

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If it only vibrates when you are breaking, you could also have a warped disc rotor, which would just require the discs to be machined (not a biggie either).