Is selling homemade clothes online successful?

Hi! You shouldn't be comparing Victorian corsets to everyday branded clothing. They obviously do not cater to the same market. As your customized vintage corset is one special niche, you need to present it in a way that you will reach your targeted market. Join groups and participate in forums dedicated to these niche, and it won't be far for you to get interested buyers. Etsy is a good place since people go there looking for handmade crafts, and eBay, it its own way can also be a good exposure for its steady traffic. :) Good luck to your business venture. :)