said by evititoe:
"Portal arrangement"? Are you talking about some sort of walled garden?
I usually leave the wireless wide open. No encryption. No authentication. No throttling. The most I've done is send them to my website first, before they can continue on with their regular surfing. For private conferences, etc, I'm sure they would want encryption so that only authorized users could get on.
That is the definition of portal. Users are not able to access the Internet until they have authenticated through a portal page. That is where you collect charges for services.
You don't need wireless encryption to manage Internet access in fact you normally do not want to use it because it will make it much more difficult to manage.
This other thing to consider is make sure you enable port isolation. Since computers are bridged you don't want users to be able to see each other, especially if they have file sharing turned on.
As to reasonable price I have not idea, combination of your cost and what the market will accept.