You can buy gold with real $/£ but not game dollars. Also the tournaments are a good way to get 50 gold a week so long as you maintain your position between 650-3000.
The quickest way to get Gold without spending real money is to trawl mazes. Eg Siberia onwards. Stashes are random awards of Dollars, Energy, Gold or Stamina.
The most efficient is probably St Louis - Spikes Villa as this only takes 52 energy to complete with 9 stashes. The second maze, Spikes backyard, takes 63 energy for 9 stashes. The third maze 72 energy for 9 stashes.
All figures are not collecting scratchers, as this will make your energy toll 30 more per territory,
Jamaica and Milan are 15 per scratcher so this raises to 48 energy for Milan and 102 energy for Jamaica.
Bangkok 1st maze 92 energy 10 stashes 2nd maze 116 energy 10 stashes 3rd maze 68 energy 9 stashes
Madagascar 1st maze 88 energy 11 stashes 2nd maze 90 energy 11 stashes 3rd maze 90 energy 10 stashes
Jamaica 1st maze 132 energy 18 stashes 2nd maze 132 energy 18 stashes
Cannes 1st maze 77 energy 11 stashes, 2nd maze 80 energy 11 stashes, 3rd maze 119 energy 19 stashes
Kiev 1st maze 68 energy 10 stashes 2nd maze 76 energy 10 stashes 3rd maze 96 energy 10 stashes
Greenland 1st maze 72 energy 9 stashes 2nd maze 68 energy 9 stashes 3rd maze 66 energy 9 stashes 4th maze 70 energy 7 stashes
Palermo 1st maze 72 energy 8 stashes. 2nd maze 78 energy 9 stashes. (Volcano) 3rd maze 54 energy if you ignore the scratchers with 9 stashes. 4th maze energy stashes
Cuba 1st maze 78 energy stashes. 2nd maze 78 energy 9 stashes. 3rd maze 98 energy 9 stashes. 4th maze 92 energy 10 stashes.
Milan 1st maze energy required can vary as you have to roll dice to play. At 2 lightning per spin of the dice if you rolled a friendly number every time and got the key straight away a minimum of tens spins is needed to get to the end of Club, with 5 stashes.
2nd maze Similar to 1st 35 steps so at least 9 spins at 2 energy each for 6 stashes
3rd maze dependent on how many cheerleaders you have if less than 4 (4 star) cheerleaders you can not beat bartender.
The Siberia maze 1 132 energy for 14 stashes and maze 2 148 energy for 17 stashes. + scratchers