Honestly I don't see any available modules out there about this type of limitation and control group but it might be some way to do it manually like if anyone made payment then you upgrade user account manually to paid group...maybe in dle script developer website will have some module for integration

You can ask admin at http://dle.net.tr/ he might be able to help because he's very good developer

It depends how you design your site. I mean if its something like paid VIP members and free stuff for them then you may need to modify few the module your self but I saw few modules on internet for same purpose.
but if you want to sell digital goods with different prices for any register rememberer then you can try few modules
http://www.dle9.com/moduli/3242-modul-dle-100-shop-11-internet-magazin.html
http://www.dle9.com/moduli/besplatnye-moduli/3965-dle-billing.html
http://www.dle9.com/moduli/platnye-moduli/3828-internet-magazin-v10.html

there are many more but you will have to translate them.

Thanks guys for your replies.For now I have set up the page only accessible by certain group (authors) and I will be updating users manually.When the site is fully up and running I will look into modules.