Cowboydoc, I certainly won't argue with you. I think it would help the discussion to know if this is being done to earn a living or as a hobby.
If I was to make a living at it, I would like good reliable equipment.
100 acres for me would mean staged cutting, ie in 33 acre portions. I know in other areas this can't be done for all kinds of reasons. The weather here is just not reliable enough to cut 100 acres and bet it all!
A family I'm friends with works something in the order of 1000 acres. They do round bale silage so 3 of them work 18 hr days for 6 weeks every summer. I'd bet there is a million bucks of equipment tied up in their operation though.
My opinion is 2 people with 30-50 000$ to spend should be able to effectively harvest 100 acres of hay, that is if a round or big square baler is bought. Small squares, well, good luck with 2 people! We're attempting say 3000 small squares this year with all 3 people who work full time elsewhere, fun fun!
Ken