Here's my take on it, which I now notice looks decidedly similar to at least one other example. Without the possibility of commas as thousands-separators, it's about half the length it is here. Also, note that the plus/minus must always precede the dollar sign (to fix this, make [+\-]?\$? into (([+\-]?\$?)|(\$?[+\-]?)). (Can those parens be eliminated somewhat? I don't know off the top of my head.)

#!/usr/bin/perl -w

# bunched up: /^[+\-]?\$?(\d+(\.\d+)?)(\d{1,3}(,\d\d\d)+(\.\d+)?)$/
$match = qr/^
    [+\-]?        # optional sign
    \$?        # optional dollar
    (        # version without commas
        \d+        # one or more digits
        (\.\d+)?    # optional decimal-plus-more-digits
    )
    (        # version with commas
        \d{1,3}        # one to three digits
        (,\d\d\d)+    # groups of three
        (\.\d+)?    # optional decimal-plus-more-digits
    )
    $/x;


while (<DATA>) {
    chomp;
    print "$_: ".(($_ =~ $match) ? 'num' : 'non-num')."\n";
}

__DATA__
1020
$10.21
-1023
+1.024
beer
10$25
-$102.6
A1027
10,000
15,00,000
10,000.001 
1028$
$
$-1.029
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--grendelkhan