Sometimes these situations are ambiguous, and confusing. In some cultures, this would be a normal part of doing business and it's commonly accepted. In some places, you can even claim these 'bribes' against tax...!
Generally it comes down to being comfortable with your choices, and ensuring that everything you do is completely legal.
If you need to invest $1,000-$2,000 for a lawyer to write a legal opinion, and this will make it likely to safely get a deal worth $15,000, it may be the right decision.
Good luck!
I've never been in the situation where there was the illusion that what was talking place was ok. It's dirty, cloak and dagger (making gifts or payments is always an exercise in creativity) and heads generally roll if it's exposed.