I'm with LanX, I don't really see how it would make sense to iterate the loop multiple times if price doesn't change, but if you really want a tight loop, everyone loves threads:

#!/usr/bin/perl -w
use strict; use warnings;

use threads;
use threads::shared;

my $PRICING :shared = 0;
my $RUNNING :shared = 1;


sub price_thread {
    while ($RUNNING) {
        # Local variable to limit lock time.
        # Catch errors in eval
        my $pricing = eval {
            # Net::Curl to remote URL... request here.
            my $val = 1000 * rand(); # [from net::curl]
            # ... more?
            # last line will go to $pricing and $pricing gets undef on
+ exception
            $val
        };

        do {
            lock($PRICING);
            $PRICING = $pricing;
        };

        # Optional pause between requests:
        sleep 60;
    }
}

sub main_loop {
    # Local variable to limit lock time and prevent changes mid-comput
+ation
    my $pricing = 0;
    while ($RUNNING) {
        do {
            lock($PRICING);
            $pricing = $PRICING;
        };

        # Optional - I don't know what you are doing with pricing, you
+ might want
        # to use 0 or undef to signal a request error (i.e., out-of-da
+te data).
        next if !defined($pricing) or $pricing == 0;

        # Do something with $pricing;
        print "$pricing\n";
        sleep 1; # Work simulation

        # return if QUIT CONDITION;
    }
}

my $thr = threads->create(\&price_thread);
eval { main_loop() };
$RUNNING = 0;
$thr->join();
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