You can take another sim along if he/she is part of your household.
But don't worry about leaving him behind, because while your sim is travelling, the time does not advance at the home town. Everything will be like you left it.
Travelling to China shouldn't cost 11k simoleons. Shorter trips are cheaper, and when you are there, you can for example collect rare ore and gems etc. to make something back. If you do some missions while there, you will get some money as rewards, too. Travelling is fun, and you can get some items you can't get from anywhere else, so it is worth it in my opinion.
A word of warning: travelling is usually safe, but there are many game glitches and bugs related to it. Before you send your sim off, it's recommended to make another save file by "Save as...", just in case. If something goes wrong, you can then go back to your previous save and not loose all your gameplay. I have had my save file become corrupted due the travel more than once, so I never travel without making a new file.