This year the points table for challengers had the following view:
Point table. W F SF QF R16 R32 R64 R128 Q
ATP Challenger Tour $125,000 + H 125 75 45 25 10 5
ATP Challenger Tour $125,000 110 65 40 20 9 5
ATP Challenger Tour $100,000 100 60 35 18 8 5
ATP Challenger Tour $75,000 90 55 33 17 8 5
ATP Challenger Tour $50,000 80 48 29 15 7 3
ATP Challenger Tour $35,000 + H 80 48 29 15 6 3
Prize money grades in € were: €30K+H, €42.5K, €64K, €85K, €106.5, €106.5+H
Judging by 2014 calendar, I guess they change only the minimum grade in S