The cheapest way is to get a padded bra and wear a top over it... it should keep the form...
for weight some people stuff the bra with self made inlays... a piece of stockings filled with rice for example...
wash the stockings first to get rid of chemicals... there are manuals on how to make the inlays on the internet...
well the other way is to look for a good gender therapist and get a letter for hrt...
or going the informed consent route... a good therapist might be an idea nonetheless...
which country are you from ?