Xbox Live Gold 12 month subscription for $42.55 (£25.90) from CDKeys.com
Ozgameshop is the closest international provider at $57 and ebay at around $50. Local guys are off the planet at $80 a pop.
The code is mailed to you off CDKeys. Their list price is £25.90 but if you like them on facebook they give you a 5% off voucher code (currently its CDK0909 but changes periodically) which drops the price to £24.60 ($42.55)