Hydro grows faster because in soil the plants have to search for nutrients and water. In hydro setups they are constantly being bathed in each of these so instead of using energy looking for these it can use its erergy to grow and expand its roots. Hyrdo setups a lot of times have extensive roots compaired to soil which also helps the plant grow much faster. As if you should spend $10 to buy it, I would say you should read on growing first because if you know nothing on it then you are going to end up spending $10 on something that will not turn out well at all. Also depends on what kind of plant it is. If it is some plant that he grew from seeds from a shitty bag then no way in hell would I, but if it were a good strain and you knew it was female already then it could be worth it.