Java, 246 * 80% * 50% = 98.4 bytes

int p,c,s;String m(int[]a){p=s=c=0;c--;String o="";Arrays.sort(a);for(int n:a){if(s==0) o+=s=n;else if(n-p==1)c++;else{o+=t()+", "+(s=n);c=-1;}p=n;}if(c>-1)o+=t();return o;}String t(){return "-"+(""+p).substring((""+p).length()-(""+c).length());}

int p, c, s;

String m(int[] a) {
    p = s = c = 0;
    c--;
    String o = "";
    Arrays.sort(a);
    for (int n : a) {
        if (s == 0)
            o += s = n;
        else if (n - p == 1)
            c++;
        else {
            o += t() + ", " + (s = n);
            c = -1;
        }
        p = n;
    }
    if (c > -1)
        o += t();
    return o;
}

String t() {
    return "-" + ("" + p).substring(("" + p).length() - ("" + c).length());
}

import java.util.Arrays;
public class A {
    public static void main(String...s) {
        A a = new A();
        System.out.println(a.m(new int[] {1, 2, 3, 4, 5}));
        System.out.println(a.m(new int[] {3, 4, 5, 9, 10, 11, 12}));
        System.out.println(a.m(new int[] {149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160}));
        System.out.println(a.m(new int[] {109, 110, 111, 112, 113}));
        System.out.println(a.m(new int[] {19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29}));
    }

    int p,c,s;String m(int[]a){p=s=c=0;c--;String o="";Arrays.sort(a);for(int n:a){if(s==0) o+=s=n;else if(n-p==1)c++;else{o+=t()+", "+(s=n);c=-1;}p=n;}if(c>-1)o+=t();return o;}String t(){return "-"+(""+p).substring((""+p).length()-(""+c).length());}
}

1-5
3-5, 9-2
149-60
109-3
19-9

I'm pretty sure it can be made smaller though, the t() function looks a bit messy and big.

Java, 252 * 80% * 75% * 50% = 75.6 bytes

int p,c,s;String m(int[]a){p=s=c=0;c--;String o="";Arrays.sort(a);for(int n:a){if(s==0)o+=s=n;else if(n-p==1)c++;else{o+=t()+", "+(s=n);c=-1;}p=n;}return o+t();}String t(){return c>=0?"-"+(""+p).substring((""+Math.abs(p)).length()-(""+c).length()):"";}

int p, c, s;

String m(int[] a) {
    p = s = c = 0;
    c--;
    String o = "";
    Arrays.sort(a);
    for (int n : a) {
        if (s == 0)
            o += s = n;
        else if (n - p == 1)
            c++;
        else {
            o += t() + ", " + (s = n);
            c = -1;
        }
        p = n;
    }
    return o + t();
}

String t() {
    return c >= 0 ? "-" + ("" + p).substring(("" + Math.abs(p)).length() - ("" + c).length()) : "";
}

import java.util.Arrays;
public class A {
    public static void main(String...s) {
        A a = new A();
        System.out.println(a.m(new int[] {1, 2, 3, 4, 5}));
        System.out.println(a.m(new int[] {3, 4, 5, 9, 10, 11, 12}));
        System.out.println(a.m(new int[] {149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160}));
        System.out.println(a.m(new int[] {109, 110, 111, 112, 113}));
        System.out.println(a.m(new int[] {19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29}));
        System.out.println(a.m(new int[] {1,10,11,16}));
        System.out.println(a.m(new int[] {-3,-2,-1,0,1,2,3}));
        System.out.println(a.m(new int[] {-3,-2,-1}));
    }

    int p,c,s;String m(int[]a){p=s=c=0;c--;String o="";Arrays.sort(a);for(int n:a){if(s==0)o+=s=n;else if(n-p==1)c++;else{o+=t()+", "+(s=n);c=-1;}p=n;}return o+t();}String t(){return c>=0?"-"+(""+p).substring((""+Math.abs(p)).length()-(""+c).length()):"";}
}

1-5
3-5, 9-2
149-60
109-3
19-9
1, 10-1, 16
-3-3
-3--1

Update:

It can now handle negative numbers as well, adding to the bonus.