If cost is a criterion, then why cremate? My wife and I decided years ago that when either of us kicked the bucket, then the other one would bury the deceased. She died about a year ago and was buried in the local village cemetery without any fuss or carry on. The total costs were under €1500 including transport, undertakers' fees, coffin, burial site and help from the communal authorities.
Also, as an environmentalist, I would not consider cremation as viable. Providing an approved coffin for transport is alone quite costly and am pretty sure that the airlines would add many kopecks to the bill with a few more for the accompanying passengers, as well as spitting out large quantities of greenhouse gases for their pain. Burial or immersion in the sea would certainly be far cheaper and environmentally preferable.
The main objection to burial seems to be the 5 or 6 m² of land occupied by the cadaver. In many places, a part of the cemetery housing all the 20-or 25-year-old cadavers is dug up to make room for new ones – land is thus recycled – while any bones or objects are reverentially placed in a charnel house. Some other countries simply burn any remains that are dug up, without ceremony.
We have been burying bodies for many thousands of years as being the best environmental and economic method of disposing of them. It does not make sense to seek polluting methods of disposing of the bodies.