Rather than bribery, I would appeal to "now or later".
"Honey, there is a really good expansion to my game coming out in a few months sometime. As you know, I was a beta player during the initial release and rather than waiting for the release, I can join the beta for the expansion too. Cool, huh? What do you think, should I get the expansion now, or later?"
This is actually pristine and has worked for me multiple times, then again I don't use it very often. However, when I do use it, i make sure to be precise about it.
This way when you need to use bribery for something, it won't be tainted by other situations where bribery has been used. A person will categorize norms by grouping, so you can control what groups she is likely to associate certain behavioral cues and terminology with. My woman knows that when I ask "now or later", its usually a small thing (to her). Likewise, when I use bribery, its to get out of something in advance or afterward.
Never ever mix your groupings however because you don't want to use bribery for something which requires it and have it cheapened in value by all the other times you used it. Absence makes the heart warm, trust me.
That said, just think of a few different techniques you can use for specified inconvenience levels and be concise about it. develop continuity that you "only use bribes here" and "now or later" there for example. That way, when you perform one of them, it will conjure a mental picture associated with prior experiences and tell her "now or later... hmm..." This will help you both. It will eliminate confusions in communication, and you might notice her begin to perform imitation; using the same or similar cues for grouped behaviors. We are all machines, so knowing it and using it isn't manipulation if you are always up front about your goal. You are simply "directing traffic" on the "road there". 
