oikura desu ka?

What if you are at a shop and cannot find a price tag, what to do?

Yes, you need to ask the price. How?

Sumimasen, ikura desu ka? or more decently,
Sumimasen, oikura desu ka?

What is this "o" in front of "ikura"?
This "o" is a prefix showing politeness. It just sounds nicer.
This "o" can attach to most of Japanese words, but not all of them.

Examples:
kane -> okane money
heya -> oheya room
sushi -> osushi sushi
miyage -> omiyage souvenir
denwa -> odenwa telephone

Also, you cannot attach "o" to foreign words.
Thus, we don't say "okonpyuutaa"(computer) or "otakushii" (taxi)

Some words start with "o", but it doesn't mean polite or not.
e.g.  ohayoo (good morning). However, "hayoo" doesn't make sense.

dewa mata!
-Kazue
http://learnjapanese123.com