They do buy on the Intentional market but their sources are limited. Having their own might be more cost effective.
I don’t see sources significantly limited. The change in sources was more do to the construction of the BakuTbilisiCeyhan pipeline. This provided another Million Barrels a day to the region, and reduced cost of bringing oil to area.
There is so little known about the newly reported drilling in the Golan. From my perspective, the information that was not released is rather suspect.
Israeli petroleum is mostly imported from former Soviet nations, via the Baku-Tbilisi-Ceyhan (BTC) pipeline, connecting the Caspian Sea with the Mediterranean, and passing through Georgia and Turkey.
http://energy.gov.il/English/Subjects/Subject/Pages/GxmsMniIsraelsFuelEconomy.aspx