How about instead of people being able to rent them so easily, why not make it so there are only a set amount of adverts at spawn, maybe say 5, all in set positions. This will reduce the issue with loads of holo's at spawn. These will all have 1 hour timeslots.
Maybe there'd be a plugin for this - that'd take an extremely long time to make, but each timeslot is available to bid on maybe 48 hours before it's time to start, and bidding would close maybe 30 mins - 1 hour before. So say we have 5 advert slots at spawn, and you want to bid on the 14:00 timeslot on the 24th June 2014, and bid 50000 meebles.
Command: /pholo bid 24062014 1400 50000 == /pholo bid [date(daymonthyear)] [time] [price]
You'd receive a mail or alert each time you are outbid or win a bid, and there would be broadcasts when timeslots are released and closed, maybe with a broadcast 10 mins and 1 min before closure too.
There's a chance I'm over-complicating this, but it would reduce the density of pholo's and would be more interesting, with battles for timeslots where lots of users are at spawn.
