Blossom End Rot

[Bella420]

OK I have this Tomato plant. Every tomato it has given me has had this end rot. I know now that a calcium deficiency causes and when I went to my grow shop they said i needed some calcium stuff which was quite expensive. It had some oyster shells and stuff like that in it I think. What I want to know is what would be a more economical product to put in instead of spending 50$ on this plant supplement? Organic of course if possible. :)
Thanks Ev1

[Growdude]

Cal -mag will give you what your looking for.
hxxp://hydroharrys.com/catalog/product_info.php/cPath/16/products_id/2370?osCsid=24303c6645cfd6f24decdd809e865987 (http://hydroharrys.com/catalog/product_info.php/cPath/16/products_id/2370?osCsid=24303c6645cfd6f24decdd809e865987)

[Bella420]

tysm!! MY grow shop is sooo expensive on stuff and I don't need 10 gallons or however much that huge thing they tried to sell me was. I know now for next time!