i had one of mine cracked like that too. passenger side i believe. not too big of a suprise tho on a car with about 140k miles at the time. replaced with sprint springs and noticed a huge improvement. still have a damaged strut mount tho. good luck with the struts whenever u put them in.
they arent too expensive...i think i payed around 200 for all 4 w/ shipping. that was a decent deal on ebay tho. dunno if u cud find them that cheap anywhere else.