For what it's worth, I used to practice criminal defense law a long time ago, in a galaxy far, far away (that being said; my license to practice is no longer in good standing in any jurisdiction; what follows is a discussion of general legal principles and should not be construed as or relied on as legal advice).
1) There's a huge, huge problem with trying to "beat a rap" using an entrapment defense. Basically, when you "plead" entrapment you
must admit that the conduct for which you have been arrested is a crime. In other words, half of an entrapment defense is in fact a guilty plea. The "defense" part of it is the kicker: you are then have the burden of establishing by at least some evidence (note: the actual legal burden varies from state to state; consult a lawyer in your jurisdiction) that you wouldn't have committed the crime but for the enticement by LE. If you don't convince the jury of that, you lose. And note: if you have prior convictions for the offense you're accused of, forget about pleading entrapment (as a practical matter). If the prosecution can prove that you had a "predisposition" to commit the offense you're being tried for, that pretty much negates an entrapment defense. Prior convictions for the offense you're being tried for now are (IIRC) admissible to establish your predisposition to commit the crime you're charged with.
2) As a practical matter, cops can (and do) lie like rugs under oath. All. The. Time. (My rule of thumb when I was in active practice: "If a cop testifies that the sun rose in the east that day, don't believe it until you get independent evidence of that fact.") If the case comes down to an issue of your word against his, you've probably lost; it's going to be very, very difficult (usually impossible) to prove to the satisfaction of a judge or jury that the cop is lying. (It does happen, but not enough to bet your freedom on it.)
3) Legal and medical advice you get on the Internet (especially on USENET or on message boards) tends to be worth every penny you paid for it.
If you have a real legal issue, pay the money to talk to a lawyer admitted to practice in your jurisdiction. It's worth it.
Cheers,
bcg