The combinations (15):
04 07 10 14 27 31…08 18 19 22 33 35…03 05 06 11 17 20
12 15 21 28 34 36…02 09 23 24 26 32…01 13 16 25 29 30
01 03 08 09 19 20…01 04 08 10 19 22…03 04 09 10 20 22
11 16 28 30 31 36…11 12 28 29 31 32…12 16 29 30 32 36
05 06 14 15 18 27…05 07 14 17 18 34…06 07 15 17 27 34
The total cost is $30.
Babar 
04 07 10 14 27 31…08 18 19 22 33 35…03 05 06 11 17 20
12 15 21 28 34 36…02 09 23 24 26 32…01 13 16 25 29 30
01 03 08 09 19 20…01 04 08 10 19 22…03 04 09 10 20 22
11 16 28 30 31 36…11 12 28 29 31 32…12 16 29 30 32 36
05 06 14 15 18 27…05 07 14 17 18 34…06 07 15 17 27 34
The total cost is $30.
Babar
