There's probably a less complicated way to do it, but here's what I came up with:
assign("buyin", max(1 + if(bc > 50, 1) + if(bc > 110, 1) + if(bc > 220, 1) + if(bc > 330, 2), 6))
assign("player", 2 + min(floor(max(0, n - 11) / 10), 4) * .5 + if(n > 50, 1))
assign("pos", switch(r, 1, 150, 2, 120, 3, 100, 4, 80, 5, 60, 6, 50, 7, 40, 8, 30, 9, 20, 10, 10, 6 - min(floor((r-1)/10), 5)))
buyin * player * pos