3-4 days in Izu

I have 3 to 4 days in Izu Peninsula. Which free pass should I get for traveling around West, East & South of Izu.

How about the Izu Free Q Kippu? It also includes access from Tokyo:
http://www.japan-guide.com/e/e2358_006.html

The Izu Peninsula is also a very attractive region to be explored by car:
http://www.japan-guide.com/e/e2024.html

Thanks but sorry I will be going to Mt Fuji before coming to Izu. So Izu Free Q Kippu would not be a good deal. What about Minami Izu Free Pass as it covers Unlimited usage of Tokai buses in southern Izu. I hope to cover thses place:
1) Kawazu Seven Waterfalls
2) Irozaki Coast
3) Dogashima
4) Shuzenji
5) Heda
Like to say 2 night in Shimoda, a second night in Dogashima or Toi? But could not get a cheap accomdation in Dogashima or Toi. Any advise?

Tozai Bus' Minami Izu Pass sounds like a good pass for you, but it only covers buses as far as Dogashima. You would have to pay separately to get to Heda and Shuzenji:
http://www.izu-station.com/sub/tokutoku/tokutoku-10.htm

More passes:
http://www.izu-station.com/sub/tokutoku/tokutoku-top.htm

Do you know what is the cost for Izu Express Line & what is the regular fare for the Tokai buses?
Do you have any cheap accomdation for Dogashima? TQ

The fares for the Izu Express can be looked up here, but note that Shimoda's station is called "Izukyu Shimoda":
http://www.jorudan.co.jp/english/norikae/

Bus prices in Japanese can be looked up here:
http://www.tokaibus.co.jp/