After filling in numerous surveys I managed to earn a $20 gift card, but after 60 days my gift card still hadn't arrived so I contacted Mint Surveys. It took over a fortnight to receive a reply but they have agreed to send me a replacement card. I have since earned a further $30 gift card, which arrived within 3 weeks. Overall, I'm happy with the service, although the remuneration is quite low for the amount of time it takes to fill out surveys.

Approximate cost: $0