Hi Janet,
These days you can apply for and receive a 60 day tourist visa in your home country or in one of the countries close by to Indonesia and that 60 day visa can be extended at 30 days a time for 250,000 rupiah.
You will need a sponsor for this extension but seeing you will have been in Indonesia for almost 60 days by then you will have made numerous contacts - one of whom could be your sponsor.
Here is a recent post on LP Thorn Tree where timdog explains this very well.
www.lonelyplanet.com/thorntree(...)ID=18674415#18674415
Read Post 2. by timdog.
The number for the tourist visa is 211 which is the same as the SOSBUD visa you mentioned above which requires a letter from an Indonesian sponsor with a current ID.
This type of visa requires a lot of planning and so on.
What will you be doing during your 3 months in Indonesia - staying in one place or moving around the country side.
Also where will you be in Indonesia during this 3 months?
Pamela.