Fish oil in a bottle is the cheapest option.
This is a reputable supplier and Carlson or their in house brands are both good. Both do not taste of much and do not repeat on me.
How much is more complex but you are probably looking at 500mg of EPA and 500Mg DHA minimum.
You may find this thread interesting if you have not seen it.
http://www.vitacost.com/Carlson-Norw...iver-Oil-Lemon
http://www.vitacost.com/NSI-Liquid-N...HA-Lemon/cas-1