This is how I revised my formula (with the proper fields):

=SUM(MIN(CEILING(B17,1000),Calculations!A29)*Calculations!B28,MAX(0,MIN(SUM(Calculations!A28:A30),CEILING(B17,1000)-SUM(Calculations!A28:A31)))*Calculations!B29,MAX(0,MIN(SUM(Calculations!A28:A31),CEILING(B17,1000)-SUM(Calculations!A28:A31)))*Calculations!B30,MAX(0,MIN(SUM(Calculations!A28:A32),CEILING(B17,1000)-SUM(Calculations!A28:A32)))*Calculations!B31,MAX(0,MIN(SUM(Calculations!A28:A33),CEILING(B17,1000)-SUM(A28:A33)))*Calculations!B32,MAX(0,(CEILING(B17,1000)-SUM(A28:A33)))*Calculations!B33)/1000

B17 = the value (or price)

It kicks out a completely wrong #.