Perhaps you can consider a membership where people pay a fee that is taken out once a month but you only have to sign up once and it comes out automatic. Then you can download everything that comes out that month.

Example Except I think the monthly is easier on a budget and people are more likely to stay members than to have to try and come up with the full payment all at once.

This site offers a subscription where you pay monthly and it is much easier on the budget. So I am more likely to keep it. Also for you it would be easier to budget a monthly income.

Just an idea for you to consider.