I am basing my reply on my own experience of what we did last year.(im no expert!)
Last year in July i bought 10 goslings 3 days old with the idea of rasing them for xmas they were in the stables on heat for a while then once they had feathered up they were aloud to free range our holding coming in to the stables at night,they quite happly hung around the yard until i opened the door or if i had left the door open and it was late they would be in there stable,they were fed twice a day with mixed corn,my adult geese took them under there wings and taught them all they needed to know about life it was lovely to see all going well but as the months passed although they grew well they werent growing enough to be ready for people who wanted a large goose,i happened to be picking some of our sheep up from the butcher and was chatting away to him about it and he said that for the last 4-5 weeks the commerical guys keep them penned and off grass and basically pump them full of feed to fatten them up,but thats not for me as i went into this wanting them to be free range right up until the end,so i desided to keep them free range and not sell them we picked a couple of the bigger ones which we had for ourselves at xmas,luckly a friend 'did' them for us so no costs apart from a free duck!
I still have what was left and i was very luckly the last boy i sold today the rest are female and i have desided to keep them if they were male might have been a different story.
Points to consider
Although the price of geese meat is high i have learnt that is for a reason,they need to be under heat for a few weeks,if you have too many under 1 lamp they will easily squash each other with no mercy,when they are young thay eat a great amount and then even free ranging they still need corn to help them grow.
Costs of the kill,gut and pluck,geese are a nightmare to pluck which is why i didnt mind giving my friend a duck in return for doing it.
Around me there is no one who can kill,pluck and dress so i can sell them to the public my nearest is 15 miles away,friends and family are different.
Not trying to put you off in any way but i think you need to consider all the facts and work out if all the work and costs with getting them to be able to sell to the public is worth it for such a small number that you would be able to take.
Also unless you have some goslings in mind we are late in the geese season for them,mine stopped laying last month,but if you have found some adults then its a whole different story.
Hope this helps
Karen