Call the company and let them know you have plan going on a trip next week, and ask if they can postpone the interview after you come back or have the interview before you left for the trip. Most companies will accomodate this kind of situation. If they cannot make other alternatives, then you may want to tell them you really would like to attend the interview; but the circumstances won't allow you to do so; and thank them for the consideration.
Not to mention my choice! I don't know if I should regret it
I don't want to give advice because:
1. If you are influence by my advice and later turn out regretting it, you will blame me and ultimately blaming yourself.
2. There are no right or wrong choice here: If you give up the package and go for the interview but turn out not getting the job - you will regret it. If you don't interview, after you come back and have to look for job again, you will regret it.
The best scenario is you take the interview and get the job. so the question is: what do you think of your chance? how much you like the job?