Cheap Beach for Poor University Students

My friends and I are university students in southwest Tokyo prefecture. We would like to get some sun/beach over Golden Week 2009.
What is the ABSOLUTE cheapest place to go, accommodations, mode of transportation?

Just hop on a local train to Miurakaigan or Kamakura or the Boso Hanto area, depending on your departing station and enjoy your day trip.

But if you wish to stay over, you might as well reserve a minshuku and go to one of the beaches by bus from Shimoda Station. To Shimoda, you can use local trains to save money.

I hope there are still vacancies.

CJulian, are you actually after hot weather, i.e. wanting to go swimming and sunbathing? If so, I'm sure you realise that it's not really warm enough by GW in Kanagawa and Shizuoka to do that (unless you are a lot tougher than I am!)

Can you be more specific about what you are wanting to do? Somewhere in Japan or overseas? Swimming and sunbathing or just being near the beach? If you want to go somewhere that is flying distance and means finding accommodation, I'm sure you also realise that not only would most places have been fully booked for some time, prices for transport and many hotels triple, if not quadruple, over GW, so the chances of finding somewhere cheap to go are pretty low.

Haven't been there myself, but it is quite a popular place for young students to go and enjoy themselves. Not sure of the costs but you can camp there so all you need is a tent and some clothes.
I've got many friends who have been there and often go there every year for GW to swim and take it easy.

Going to Niijima is a good option. They have free camping on a first come first serve basis and you can get there by ferry from Tokyo. The beach isn't really a sand beach but more like tiny pebbles. It'll be a bit cold now but swimming on a sunny day is an option (I've done it many times myself during GW)

Shimoda is good too but tends to be quite crowded during GW and in recent years they've been cracking down on camping outside of designated areas. Good luck finding accommodation this late in the game in Shimoda. It will be completely impossible to find anything cheap and cheerful...
Have fun! Go to Niijima!!