Business class tickets from the USA in lie-flats are typically not cheap if you're paying cash. There really isn't any way around this (the occasional business class fare sale notwithstanding).

The most cost-effective way of doing this (assuming you are based in the USA and can apply for credit cards) is through either generating miles through multiple credit card applications or through manufactured spend (there's an entire forum dedicated to this topic on FT).

Alternately, you can purchase miles. Alaska Airlines, Avianca and US Airways are selling miles for approximately 1.5-2 cents per mile, making a round trip in business class approximately $2000-2500 US per person, a first class trip around $3000 or more.

(Note that US Airways and Avianca require pre-existing accounts in order to buy miles, you cannot just sign up to immediately buy miles. The US Airways account needs to be 12 days old, and the Avianca account must have existed prior to the sale's announce date of 9/2).

Finally, the Mileage Run forum contains "Good Deals" thread for economy and premium class fares that may help you.