Price: It cost me 22.60€ but I don't know if you can get it a little cheaper in other countries.
The bottle: it comes with 118ml of product. I don't think the bottle is too big, but it isn't small. I think it's going to last me a really long time.
How I use it: I spray it about 3 or 4 times on my face right after I apply my make up from a 20-30 cm distance. I don't measure it but I like spraying it from a distance so it doesn't actually wet my face. It dries pretty quickly anyway.
Results: I feel like my make up does stay longer. It claims 16 hours but I just haven't worn make up that long, so I don't know if it's actually true or not.
It can also be used to hydrate your face when it's cold outside. I heard some people say they spray it also other times during the day to make their faces feel more fresh, so I guess you can also do that.
Overall, I really recommend this product to all of you; and even though some people may say it's a bit pricey, it's going to last you a long time and it's worth the money.