A Vickers or Maxim in 8mauser.
If neither of those are available, a Browning 1919.
Now, either of those will be complete with tripod, ammo cart, and a linking machine.
If there's any dosh left, a Colt potato-digger and/or a Bennet-Mercier (former in 6mm Navy Lee; the latter in 30-40govt).
Those "add-on" selections were relatively cheap, "back in the day" as being seen as "obsolete." But, are hugely rare today, and thus command high prices.
Mind, inflation means that while the purchase prices will seem to pittances, yields today will be small in constant dollars. That's the cruel reality of inflation-sure that thing bought in 1934 for $150 might sell, today, for $40K. But, had you put that $150 in a compounding 7% annuity, you'd be far better off in terms of how big the pile of cash is.