i am an instructor myself but i teach independently. a professional response to your concern is tduhat no matter where toy go as far a studio, it will be expensive to prepare for both a showcase and/ or a competition.we ( instructors) put un lots of work mentally and physically to personalize everything we do dance related for you.if you research the ballroom industry, it costs a considerable amount of money to participate in these events. and of course it is a business so they are going to charge. you need to put more work into a showcase than regular social dancing. professional dancers train 6 hours a day 5 days a week affidavits why they look so good. your lessons are probably about 45 mins which doesn't exactly give you all the time to polish. so yes 10 or lessons may be needed.