I'm a little surprised by the hostile reception that you've gotten so far. Perhaps the phrasing has thrown people off. I don't think OP is asking FT to do the homework for him. He's obviously read many of the threads. He's asking a question that I am particularly focused on as well: if one wants to use just cash, what are the key ways to *purchase* miles in bulk?

This question is not a request to repeat the best deals on FT. Many of the FT deals are for 1,000 miles here, 5,000 miles there. I don't think that's what the OP is looking for. He wants to scoop up "hundred thousand miles".

Also, most of the deals on FT involve expending a certain amount of time and energy to get miles (e.g. apply for a credit card, get 25k miles, use cc to get to required spend level, verify miles are credited, call to cancel credit card, repeat). I think OP also is not interested in these legwork-for-miles deals. There's nothing wrong with those deals but if we assume OP has more money than time, and his goal is to buy, say, 1 million miles, what's the best way to do it if he does not have restrictions on how much he can spend?

My best suggestion would have been bankdirect but OP has said that doesn't work for him. The next best thing might be to explore his idea to band together to purchase them. If a group of us wanted to pool together to buy 10 million miles, could we do it? Perhaps we'd have to form a nominal corporation to do it. If the number's not 10 mil miles, maybe a bigger number like 20 mil or 50 mil would get their attention. At a high enough price and volume, the airlines are willing to sell their miles to partners like Bankdirect or FTD. I think for the airlines, it's just purely a numbers decision; they don't care if they're selling the miles to Bankdirect or NewcoFTcorporation.

Let's pool mental resources and brainstorm!