GEO Trust Rapid SSL is very cheap. If you just need basic ssl and not worried about name reconigition there is a free ssl out there. Google free ssl. That is what I did. Basically an open source.

You can create your own. But you would be responsible for any gaurantees of security if you state that.

If you must have gauranteed high performance then that is going to cost a bit. GEO Trust and Comodo have some good options for that.