Was wondering of payment ways like paysafe or click&buy could be added to gog?

Here's GOG's information page on payments. I don't think they plan to add those services you mentioned anytime soon. But they do accept PayPal if you don't want to use a Visa or Mastercard.

http://www.gog.com/support/website_help/payments_pricing_promos

GOG doesn't support PaySafe card probably because of the cut psc owners take with every purchase.

GOG also goes for simplicity. Few clicks and the game is yours. If you need pre-paid option, you can use PayPal as such (for example, by adding funds to it from time to time via traditional money transfer)

You can vote for this payment options on requested site features:

Paysafe card
http://www.gog.com/wishlist/site/adding_paysafecard_as_payment_method


Clickandbuy payment option
http://www.gog.com/wishlist/site/clickandbuy_payment_option