There's no easy answer. Pointe shoes off the rack are made to specifications of the woman's foot, not the man's foot. If you try to fit into a pointe shoe designed for a woman, you'll probably end up in trouble.
I took pointe class for three months and had custom made shoes. My foot was so different than a woman's that even though I tried a woman's pointe shoe, I was in pain shortly after the start. I stopped pointe classes after three months because I started to ask "Why?" What further stuff can you learn on pointe, as most of men's choreography is designed much differently than the use of the muscles you might develop from pointe work. Even centering is so different on pointe than the centering needed for the jumps a man must make. Centering on pointe becomes a static position, not the centering needed for the man in motion. Dansuers move, not maintaining the body still as the ballerina poises on pointe.
So IMHO I suggest you reconsider your decision for pointe, and take a men's class instead. If you can't afford the proper-fitted pointe shoes, your exercises will be for naught.
balletboy[/i]