Shipping is a flat $1.99 for your entire order!
Seasons 1, 3 and 4 on DVD are all temporarily out of stock but they say "more are on the way". Season 2 and 4 have NEVER been released on Blu-ray (don't ask why - I don't know). So right now you can order Season 1 and 3 on Blu-Ray - all are in stock and/or Season 2 on DVD.
I recommend ordering all the ones you want even if temporarily out of stock to save on overall shipping plus who knows when this sale will end.
Here is the link to ALL seasons in all formats: https://www.familyvideo.com/catalog/advanced_search_result.php?whatType=all&whatText=prison+break&title=prison+break&person=