Cheaper Transport Tokyo to Ogimachi Village

Hello,
I'm currently in Tokyo for 3 day until Sunday 22. I really wanna go to ogimachi village. Can someone suggest me how to get there in most effective & efficient way? Maybe to go on Saturday. How much total cost for the round trip? Thanks before.

No good using "Ogimachi town village" village name is "Shirakawa".
Ogimachi is village's town(area) name calling "Shirakawa-go".
So you should use "Shirakawa-go(Shirakawago)" if asking/searching or.
("-go" means township/-go sound is longer "gou" a bit different EN "go")

But too late post.
Already full booked chaepest way by Fri over night bus to Nagoya,Kanazawa or.
http://shirakawa-go.org/en/access/
So take Hokuriku Shinkansen "Kagayaki 501" (need seat booking/no un-reserved car)
from JR Tokyo(or Ueno/next stop) stn to JR Kanazawa stn first
https://goo.gl/maps/AMgPXkGzwaB2
http://www.eki-net.com/pc/jreast-shinkansen-reservation/english/wb/com...
then take Nohi-bus(need booking/no seat booking)
from Kanazawa stn bus stop dep 9:05 to Shirakawago bus stop arr 10:30.
http://www.nouhibus.co.jp/english/shirakawago_kanazawa.html

Hokuriku Shinkansen "Kagayaki 501" seat booking possible on the day morning
at Midori-no-madoguchi(JR stn ticket window/counter) enough.
(Purchasing Fri possible)

Nohi-bus booking by call recommend ASAP
but you can purchase on the day at bus ticket office of Kanazawa stn maybe.

Back way to Tokyo ask at tourist center of Shirakawago recommend.
What time arr hope? (21 night, Next 22 morning or?)

Can someone suggest me how to get there in most effective & efficient way?

The most efficient and effective way is to take the shinkansen to Toyama and then the bus to Shirakawago (before December 1, via Kanazawa). It is explained here:
http://www.japan-guide.com/e/e5953.html

But the above way is expensive.

If you want to save money, then you would have to use an inefficient way of travel. One of the cheapest ways is probably to take a low-cost bus from Tokyo to Nagoya or Toyama and then the highway bus to Shirakawago. Without looking up the details, I would estimate the cost to be about half of the above.