1. It's 200 dollars cheaper by train.
2. It will cost 10 more dollars by taxi.
1. It would be 200 dollars cheaper to catch the train.
2. It would be spend 10 extra dollars by taxi.
please note add (s) when plural !
1.It would be 200 yuan cheaper by taking a train.
2. It costs 10 yuan more if we take a taxi.