Free wireless access control ideas?

hi,
I've been looking into incorporating free WiFi access into my feature business and found myself in delma of how I can control the access.

the free WiFi only for people that make a purchase.

first, I thought of printing some kind of randum number (wireless code) on the sales reciept then storing this number in a database and when someone tries to go online they will be prompted with the ' Wireless Code' and my router will verify the number against the database. this sounds very nice but complicated specially that I will have basic register and limited budget.

Second, I thought to protect my WiFi network with password and customers have to come to me to get the password. this may be a problem if we're so busy and hard to control .

any ideas how I can control the access ?
thanks

There are systems out there that you can download that work about the same as the WiFi systems in airports work. The user is given an account, with a password. When you try to connect to the LAN, you're presented with a login page.

Look at http://www.publicip.net/zonecd/download.php

There are others but this one is the easiest - just burn a CD and boot from it. (Use a floppy or thumb drive to retain account info.)

thanks. I have this program but was looking for more alternatives. I did plenty of research and this looks like the best out there that is free.

thanks