I play trumpet at home. I feel a little uncomfortable playing because of the loudness. I found the Silent Brass series by Yamaha, which makes brass sound quieter, and you can still hear everything through headphones, but in my country they are very expensive. I don't need excellent sound, or some digital system, I just need to be quieter. Could you please suggest a cheaper alternative?
The Silent Brass is really just a practice mute with a microphone in it, and the rest of the system is just a cheapo headphone amp. I have one but I rarely bother putting the headphones on. So the first thing to check out would be a simple practice mute. They produce a ton of back pressure so you don't want to play on them exclusively and get used to it, but it's fine for short sessions.
If the practice mute turns out produce too much back pressure, then any other mute is an option. I find that cup mutes cut a ton of sound without affecting the feel of the instrument much at all. Harmon mutes with the stem out are even quieter but with more significant back pressure.
You should try out practice mutes in a shop. Look for the one with best intonation, that the one that detunes your horn as little as possible.
My experience with the Yamaha silent brass is awful, especially with the headphones. Last time I played with it I could barely play at the next rehearsal. I guess it's easy to overblow since the headphones kind of give you the impression that you are without mute. I found it easier to avoid overblowing with a real practice mute.
I like my Shhh mute, but you really need to try them to find out which one fits for you.
An alternative to buying a pricey mute like the Silent Brass system is to simply make your own, if you don't mind spending some time on a do-it-yourself project. When I was a poor college student looking to save all the money I could, I found instructions for making a practice mute out of a Renuzit brand air freshener with some simple electronics to hook up to a pair of headphones and it worked fairly well. A copy of the instructions is available online here. Here's some choice pictures:
The electronics portion of the project is obviously more complex than the construction of the mute itself, but if you're handy with a soldering iron (or have a friend who is!), it shouldn't be terribly difficult. Otherwise, you can simply build the mute without the wiring and put some extra padding in its place - you'll miss out on the headphone playback but it will still have the quieting effect.