Travel Bodhgaya to Kushinagar by various means of transport as there are no direct bus or train. You can reserve a cab but its pretty expensive. So, if you want to travel cheap from Bodhgaya to Kushinagar or from Kushinagar then you will have to travel the way I have explored traveling cheap between these towns.
You have to start early from Bodhgaya as you will have to change several mode of transport. From Bodhgaya you will have to travel by a shared auto rickshaw to Gaya city which will cost you Rs15. From the place where they drop you will get another auto rickshaw to the Gaya railway station for Rs 5.
There is no direct train from Gaya to Kusinagar so you will have to take a train to Patna city. The general bogy will cost you Rs20. The train time is about an hour from Gaya to Patna with stops.
From Patna you will have to take a train to Gorakhpur. The train ticket will cost you Rs 90 and the train will take about 4 hours or more depending on slow or late the train is traveling. You can get AC sleeper coaches too but it will cost you almost 7 times the cost of the general passenger class.
About fifty kilometre before reaching Gorakhpur you will have to get down in a small station called Deoria. Walk to the end of the station and walk over a overhead pedestrian bridge to the small town of Deoria.
From Deoria you will get old mahindra jeeps to another town called kasia. Mahindra jeep will charge you Rs90. From Kasia to Kusinagar is just few kilometres and an auto rickshaw will charge you about Rs50.
Kusinagar has several hotels and cheap accommodations. Its difficult to find a good restaurants from you will get accommodation ranging from Rs400 to few thousand. Most of the accommodations run by Buddhist entities are quite cheap.