Shouldn't daily advertisements be cheaper than monthly advertisements?

The advantage to daily advertisements is exclusivity -- your advertisement is the only advertisement displayed on the network for a full 24 hour period.

Monthly advertisements are displayed in rotation with all other monthly advertisements on all websites in our network. For example, if your monthly advertisement is one of 25 sold for that month, your advertisement will be displayed 1/25th of the time for a minimum of 25 days. We never sell more advertisements per month then there are days in that month.

Daily advertisements are displayed exclusively for a full 24 hour period on all member websites. So, no matter how many daily (no more than 5) or monthly (no more than 25) advertisements we sell, your daily advertisement will be the only advertisement displayed on all websites on our network for a full 24 hour period -- no other advertisements will be displayed during that time.