By Charles Scanlon
BBC News, Munsan
Eighty-million dollars might seem a lot of money to pay for a short train journey.
South Korea paid a heavy price for the one-off crossing
But that is in effect what South Korea paid to the North Koreans for permission to test the rail links they have been building through the heavily-fortified demilitarised zone.
On Thursday two trains crossed the military demarcation line - from the north and the south - for the first time in 56 years.
In the circumstances it is hardly surprising the South Koreans milked the event for all it was worth.
The government is facing domestic and foreign criticism for being too easy on North Korea. It wants to show that its policy of reconciliation is bearing fruit.
"This is more than just a train test," said the Unification Minister Lee Jae-joung at a colourful departure ceremony at Munsan station, north of Seoul.
"This rail link means the reconnection of our national blood vessels and an end to our history of national division."
South Korea has become accustomed to paying for even small, symbolic concessions from its impoverished neighbour.
It set the tone in 2000 when it paid nearly $500m for the privilege of a first summit meeting between the two leaders.
The $80m aid package for the train test will be given in the form of materials for North Korea's light industry.
The United States worries that South Korea is giving too much away to the North and undermining pressure on the regime to shut down its nuclear weapons programme.
Domestic critics say it is humiliating that the North is getting such generous aid while allowing only a purely symbolic one-off border crossing - the military rejected South Korean appeals for a regular service.
"The North Koreans are employing a salami strategy, as always," said North Korea watcher Nam Sung-wook, of Korea University in Seoul.
"They want to receive maximum economic aid for every small concession they make."
He said the same tactics apply to the North's promise to shut down its nuclear facilities.
North Korea of course wants all the economic aid it can get but not at the cost of opening its borders to meaningful contact with the outside world - and particularly not to South Koreans.
North Korea refuses to allow regular passenger services
The regime fears that ideas from abroad will quickly undermine its totalitarian control over a still docile population.
Although South Korea is growing frustrated waiting for progress on the nuclear dispute, it is still anxious to see progress on bilateral relations.
"We are in the lame-duck season now in the run up to the December elections," said Professor Nam.
"The nationalists in the Blue House [the presidential mansion] want to make haste with the North as fast as they can."
That haste has led to much speculation of a possible second inter-Korean summit meeting before the summer is out.
Price worth paying?
Even South Korea's opposition conservatives are showing signs of going soft on the North.
There are no votes to be gained in the coming election through a policy of confrontation.
South Koreans are aware that the road to reconciliation will be long, difficult and expensive. But they see little alternative.
Confrontation with a heavily-armed and now nuclear neighbour is seen as out of the question, and collapse would be an economic disaster.
In the circumstances many South Koreans think a few hundred million dollars here and there is a price worth paying.