In Sweden... on the westcoast you can rent an aircraft for 65 euro per hour and in the wintertime you'll have darkness for 18 hours per day... =)
65 is the cheapest I ever found, normal price is around 100 euro per hour...
From about 4 PM you'll have darkness and most airports are open to at least 10 PM so you can get 6-5 hours of night time per afternoon and at least 4-5 hours every morning depending on how early you want to wake up =)