Getting to Izu Peninsula

What would the cheapest/easiest way to get to Izu Peninsula from Ueno? Which trains would I have to catch and when would they be leaving?

Just about where in Izu Peninsula would you be interested in going? But in any case, you would take the JR Yamanote line from Ueno to Tokyo station, from where:

http://www.japan-guide.com/e/e6305.html

If you are going to the southernmost end of the railline in Shimoda (Izukyushimoda Station), you can get there for about 5,900 yen taking a limited express train that leaves Tokyo Station every hour on the hour till about noon.

Or you can get there for about 3,900 yen by just taking express trains which involves a lot more transfers.

I would suggest going to the Hyperdia or Jorudan websites to plan your trip.

The search below is from Ueno Station to Izukyushimoda Station on non-limited express trains.

http://www.hyperdia.com/cgi/en/search.html?dep_node=UENO&arv_node=IZUK...