Hi In our enterprise edition organsitaion we have a 1GB storage limit. Below is the screenshot for user license We need an extra 600MB data storage.Only way ,when i calculate ,this can be achieved is by purchasing additional 30 user licenses. My questions are 1)What kind of license is cheapest and will get me 20MB per user? 2)Is there any alternate, looking at the user license info?
You are on the right tracks with your calculations but have got them a touch off. This a definite good news and bad news situation. For all of this I am referring to the Salesforce documentation here
As you can see from the information in the link, Salesforce provide 20MB of data storage per user license and then for each organisation state that the data storage available is 1GB or 20MB * # users, whichever is better. You have 27 + 5 users giving you a total of 640MB of storage and so 1GB > 640MB and it works in your favour giving you a over 1.5 times the space. That is the good news (sorry if you were hoping for more).
Because of the rule *which in general works in the favour of most smaller customers) for you to hit an extra 600MB (or 1624MB when you add the existing GB to surpass it and ensure you get the extra space) you would need 1624/20 = 81.2 (or 82 as you can have part) users. This would mean you buying an extra 50 users. That is the bad news.
The not too bad or good news - you don't have to do it this way. You can contact your Salesforce Account Executive and they should be able to sell you more space separately. I can't say I know any pricing but they will be able to help you out.