"いくらですか？” seems like a common phrase taught to all students of Japanese? But, instead of saying "いくらですか？", I always used to go honorific and say "おいくらですか？".
Is adding 美化語{びかご} to "いくら" wrong? Could it ever be wrong? After all, you cannot ask yourself questions. Why is the honorific "おいくら" not really taught? "それはいくらですか？" sounds aggressive and "in your face"?
I normally say "すいません、これいくらですか。" and I don't think this sounds impolite. I think my mother uses "いくらですか。" or "おいくらですか。", and sometimes "これ、おいくら？". I think おいくらですか？ sounds politer and a bit feminine, and おいくら？ sounds feminine and elegant.
"Why is the honorific "おいくら" not really taught?"＞＞ Maybe it's because おいくらですか / おいくら is more used by older people and textbook publishers think that students of Japanese are generally young??
When you ask 「それはいくらですか」 you already make the question sound polite by including です and not dropping は. There are much more casual versions of the question, e.g. 「それいくら？」.
This question is typically used by a customer when asking for a price. You wouldn't use honorific in this case as when you address a shop assistant as a customer, you don't address someone of a higher status. If anything, it's actually the other way round, a customer has a higher status.
If we exclude words where the お／ご has become effectively part of the word (お茶）, there are two uses of honorifics, to show respect and to be polite (or sound more elegant). Your use falls into the latter category. Its more feminine but not wrong. The book "Japanese for all occasions" by Taeko Kamiya advises not adding honorifics excessively.
