While working on my script Autopilot to enable buying advertisement I started collecting information about the price changes over time, and found out that it is not actually random, but repeats every week. So here is a graph that shows the prices for 1 week and a table that shows the same thing and highlights the cheapest ones.
| Sat | Sun | Mon | Tue | Wed | Thu | Fri | |
|---|---|---|---|---|---|---|---|
| 12 AM | 49890 | 48089 | 32080 | 43022 | 47017 | 32213 | 40693 |
| 01 AM | 48089 | 19004 | 32043 | 48612 | 37768 | 35792 | 49415 |
| 02 AM | 23896 | 7435 | 32845 | 50324 | 32213 | 45439 | 49838 |
| 03 AM | 7831 | 14021 | 34475 | 47017 | 33869 | 49890 | 39308 |
| 04 AM | 8870 | 25482 | 36853 | 40843 | 40693 | 49838 | 14928 |
| 05 AM | 21458 | 8658 | 39801 | 35177 | 47250 | 43232 | 7530 |
| 06 AM | 22775 | 20310 | 43022 | 32213 | 49890 | 23896 | 8870 |
| 07 AM | 7366 | 21438 | 46112 | 32555 | 50097 | 9763 | 19060 |
| 08 AM | 20310 | 8083 | 48612 | 35792 | 48089 | 7435 | 25482 |
| 09 AM | 23447 | 9777 | 50105 | 40693 | 39308 | 8870 | 14038 |
| 10 AM | 10094 | 39347 | 50324 | 45439 | 23896 | 16499 | 8675 |
| 11 AM | 7531 | 50168 | 49229 | 48567 | 11851 | 24883 | 22794 |
| 12 PM | 19045 | 43179 | 47017 | 49890 | 7831 | 22775 | 23447 |
| 01 PM | 46167 | 32218 | 44070 | 50168 | 7473 | 11015 | 11824 |
| 02 PM | 50109 | 49244 | 40843 | 49838 | 8870 | 8675 | 7472 |
| 03 PM | 43179 | 36829 | 37768 | 48089 | 14021 | 20310 | 9777 |
| 04 PM | 31976 | 36545 | 35177 | 43232 | 21458 | 25582 | 29278 |
| 05 PM | 44098 | 49611 | 33289 | 34525 | 25585 | 19037 | 48103 |
| 06 PM | 43972 | 43972 | 43972 | 43972 | 43972 | 43972 | 43972 |
| 07 PM | 32043 | 41531 | 38967 | 36524 | 34439 | 32909 | 32080 |
| 08 PM | 48612 | 38967 | 34439 | 32080 | 32845 | 36853 | 43022 |
| 09 PM | 37768 | 36524 | 32080 | 34475 | 43022 | 50105 | 47017 |
| 10 PM | 35792 | 34439 | 32845 | 43022 | 50324 | 40843 | 32213 |
| 11 PM | 49415 | 32909 | 36853 | 50105 | 40843 | 31977 | 40693 |
Note: the table and graph timings are based on the US-Eastern Time (-5) so adjust your times accordingly. Also the listed prices are for the most expensive type of advertisements (Billboards on 20 international airports).