go here:
you will find yourself staring at an unintelligible (because it is entirely in Hungarian) webpage
leave that '1' in the top box
in the first dropdown menu pick your starting currency
in the next line, 'venni' means 'buy' and 'eladni' means sell ... click on eladni because you are selling that starting currency and buying Forints
in the next dropdown menu pick 'Budapest'
in the one below that (the third one down), pick 'Budapest' again
in the one below that (the 4th), pick the district of interest; the Vth is the dead center of the city
do nothing to the bottom-most dropdown menu
and then click at the bottom left 'KERES' (search)
you will get a list of many exchange bureaus, with addresses and realtime current rates they offer
there will be a map below the list