TinEye offers a commercial API since November last year. Interesting, though not cheap (quote follows):
# 1,000 searches for $70 USD # 5,000 searches for $300 USD # 30,000 searches for $1,500 USD
https://api.tineye.com/pricing http://blog.ideeinc.com/2009/11/18/the-tineye-commercial-api/ |