It is technically a foundation, a non profit organization website, which will allow people to make donations for the cause. Is purchasing an SSL certificate for this site a good idea?
If i have to purchase then which one is better for such a site?
honestly i would get one. they range from only $10 up to hundreds per year. The type you get should depend on how much the foundation is bringing in. If it is bringing in thousands of dollars per day/month/year then i would say go for the more expensive one (the one that has the green bar up top like banks and such)
if it is only bringing in a couple hundred, then i would go for the cheaper one to start off until the foundation brings in more.
If they were to donate via a third-party payment gateway like PayPal, you probably wouldn't need an SSL.
However, if you are storing personal details about them (but not financial), an SSL would be a good privacy tool.