Many of our younger "too young for credit card" group will go buy iTunes gift cards that can be inputted into iTunes and used to buy music.
You parents, if they are gracious could set up an allowance in iTunes for you without loaning out there card info to you as well.
Individual song prices have yet to change on iTunes, they have always been .99 cents, but there is no telling where things will go. The labels are pushing for an increase in some tracks while decreasing the price of others.
There has been an increase in price for many "full albums" from 9.99 to around 11.99, usually they contain extra tracks or a PDF booklet or video, but not always.