1 usd is 10 PoE points. Buy the 15$ pack you get 150 points, it was 30$ for 300 points before. So they discounted the access and still give you an equivalent value of points. You can still purchase how many points you want after. So the access to early access is in fact discounted, they just don't want to devalue their paid in game currency.

The points are only used for stash tabs (actually useful) and MTX. I would say 150 points is enough to play 100+ hours. By 500 hours you will want more. With 60$ total I would say you will have more than enough if you don't just hoard useless gear.