Anya, by my experience (and by what was explained to me on a travel agency), what cuts down on prices is staying out a night from saturday to sunday. If you travel on saturday then you can get back already at the next day with the normal price. If you happen to travel on Sunday, then you will have to wait till the next sunday to be able to travel back at the normal prices. In other words, you have to spend the weekend out. Or else it will be priced has a business trip. This was what happened to me when i went to Paris last Spring. I didn't have any available seats for saturday so i travel on sunday and had to stay there the full week. Yesterday i arrived late from work at my home and was full of pain on the head, so i didn't work on the site yesterday. Just had dinner and then went to bed. P.S: Remembered now another tip. The more early (in advance) you buy the ticket the more cheap it is also. If you buy with some months antecipation it will be cheaper than buying only 2 or 3 weeks antecipation.