Check these out if you're too lazy/don't have the resources for DIY tubes:
http://www.hydrowholesale.com/viagrow-viagrow-potato-planter-2-pack-5327
$5.00 ea. and would be better for marsh environments that don't see as much fluctuation in water levels like you typically see in swamps...
Another idea is sawing these in half:
http://www.homedepot.com/p/SAKRETE-8-in-x-48-in-Concrete-Form-Tube-65470075/100321209?N=5yc1vZbv35
^those come to $3.00 ea.
http://www.hydrowholesale.com/viagrow-viagrow-potato-planter-2-pack-5327
$5.00 ea. and would be better for marsh environments that don't see as much fluctuation in water levels like you typically see in swamps...
Another idea is sawing these in half:
http://www.homedepot.com/p/SAKRETE-8-in-x-48-in-Concrete-Form-Tube-65470075/100321209?N=5yc1vZbv35
^those come to $3.00 ea.