If there's not a local place at the links posted by baconbitch, you can order grass fed beef shipped from Slanker's. www.texasgrassfedbeef.com. They also have a huge amount of information on their website. They ship with dried ice, I think they'll ship anywhere in the US without a problem.
With a 30-60lb order, the cheap cuts of steak are not much more than supermarket prices. Extremely good customer service, and they'll automatically split up an order for you if you order for multiple people.
If for some reason this is truly not an option, fish oil is the way to go. Make sure you store it in the freezer as spoiled omega3's will ruin your day.
Look up the differences in nutrients between grass-fed and grain-fed, then take the supplements that aren't in the grain-fed. I don't know all the differences, (and don't have time to look it up, as my daughter is begging for my attention at the moment) but off the top of my head, I'd say CLA, fish oil, and vitamin E. And cut all the fat off of the grain-fed meat.
And yeah, look at the online suppliers. It comes out to like, $6 a pound in the end..which is nice. :)