Except, sexing is nigh impossible.... Only way around it, is to buy a group of upto 5 more, and hope your original and one of the new additions pairs off, then rehome the originals.
It's a stunning fish though, will be worth the effort.
It is with the explosion of Facebook... When it comes to rehoming recent purchases etc, try to first make an agreement with the shop for them to have the "un-needed" fish back, some will do that, otherwise, websites such as Preloved, Ebay (Local collection only) and facebook pages are a godsend. If you have a paper that you could list them locally thats another option, as well as a card in a pet shop.
Angelfish are still very popular, so i cant see you having many issues.