A question that's right up my alley. I spent the last few months booking 20 trips in Business class to fly our wedding guests to Tuscany next May. The average out-of pocket expense for each US-EU Business class ticket was $130 for the ticket only, or slightly above $300 including tax.
I've been collecting miles for a few years; for this particular project (i.e., the wedding), about 600,000 came from credit card churning, 300k from "purchases," a million from Budget car rentals, and the rest (as well as some hotel points) from coupon connection trades for TYP ticket "credits." I can't, of course, give away all the tricks of the trade, and in any case the game has changed; the TYP ticket avenue is now much less profitable than it was until last July, opportunities for "purchasing" and churning have become more limited, and large-scale car rentals are no longer allowed --
but, I have no doubts that you can generate a few hundred thousand miles with very limited expense. The key is doing some research. Nobody --I hope-- is going to spoon feed you. Keep in mind that deals, once posted on FT, die very quickly. Read existing threads about churning and TYPs. Identify the remaining churning options, and understand how to obtain "flight credit" from the Thank You Network (TYN). Keep your eyes open for opportunities to generate miles through shopping, car rentals, magazine subscriptions, etc. People generate miles for less than a penny per mile (= $1000 for a US-EU Business class ticket) all the time, and occassionally, there are opportunities to obtain miles for
much less. Good luck!