The cost of the portable toilet trailer rental depends on the size of the portable toilet trailer and the options.
When I've rented a double toilet trailer it cost me $175.00 for the weekend so that's around $87.00 per day which is reasonable.
That includes the delivery and setup as well and then they come and pick it up for me and I don't have to do anything.
If you get the higher end toilet trailers then it can cost as much as $500.00 to $800.00 for a few days of rental.
They're worth it though if you need it for a few days or so to provide bathroom facilities to your guests.