Shell Programming and Scripting

awk '
/ *\$[1-9][0-9]*\.[0-9][0-9] */ { print $1,$2,$3,"*"; }
/ *\$0\.[0-9][0-9] */ { print ; }
' fruit_prices.txt

Banana     $0.89           100
Peach      $0.79            65
Kiwi       $1.50            22
Pineapple  $1.29            35
Apple      $0.99            78

Banana                   $0.89       100
Peach                     $0.79       65
Kiwi $1.50 22 *
Pineapple $1.29 35 *
Apple                    $0.99        78

/              pattern start
 *             zero or more (= any number) spaces
\$             exactly the dollar sign
[1-9]          one digit, excluding (leading) 0
[0-9]*         zero or more digits
\.             exactly the period
[0-9][0-9]     2 digits
  *            zero or more (= any number) spaces
/              pattern end

this pattern would match the kiwi and pineapple prices in your file, which are >= 1$, and print them with a trailing "*"

/ *\$0\.[0-9][0-9] */ this pattern will match all prices below 1$ ("$0."), and print the input line (awk variable $0) unmodified.