Just to clarify:
Presale price: Price when buying directly from Ohad. Discounts are possible depending on volume and delivery date. Can be advantageous if one buys big amounts. Presale will continue until all 42 Million tokens are sold or Agoras is released. Presale price increases with time.

Exchange/Market price: Variable price on exchange (e.g. Bittrex). Usually a good option for small amounts. If you buy big amounts on exchange the price may rise too fast due to low market depth.