@Sereg Anfaug you could get away with two rune page if you set them up as general AD and AP page since most AD jungle, and some ad tank/ tanky champion can get away with it and it also they are some adc too only thing with it and you have to know some what you doing to pull it up. and it can cover most role like ap with mpen and amour/ mr can do well with some ap and support with the general ap page. I would say have a min of three rune page and 5 to 7 mastery page before you do rank.
Could and Should are not the same. If you are going to spend money(and I have) rune pages are super nice to buy by the bundle. I have all 20 and I still have to erase and reuse them. Good luck!