That approach works fine for me. Perhaps something is awry with your template?

#!/usr/bin/env perl 
use strict;
use warnings;
use Test::More;
use Template;

my $text = q#[% DEFAULT element.email = 'email' element.price = '0' %]
email: [% element.email %]
price: [% element.price %]
#;
my $out = '';

my $tt = Template->new;

$tt->process (\$text, {element => {price => 10}}, \$out);
like ($out, qr/email: email/, 'Default email used');
like ($out, qr/price: 10/, 'Non-default price used');
done_testing;
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