Yeah, Qwikpay seems to be halfway decent. But there is a whole list of resellers, many of them who use Paypal, here:
http://www.datafile.com/resellers.html
The 6 month account seems to be the best deal if you don't want to commit to a year sub. That is assuming there is plenty of content that you like posted with DF. But check them all because many of them have different prices.
If you buy one, they will send you an activation code. You log into your free account and then enter that code. Normally it's pretty quick to activate it.
And if you do get a DF account, always click on your Profile from time to time to see how much download bandwidth you have left. Most sites give you so much per day or every few days. DF gives it all to you to do what you like. So it is possible to blow through all of your bandwidth long before the account expires.