As a listing agent, I prefer to suggest buyer incentives. They help differentiate a listing, increase the pool of potential buyers (especially for properties priced in the range in which first time buyers are buying), and strengthen my seller's bargaining position.
Ultimately whether or not a buyer's agent bonus works or not is really up to the buyer's agent. Some agents will show properties with a bonus first and there are also some agents who will work harder to sell a property with a bonus.
It is absolutely ethical for a seller to offer a bonus to the buyer's agent. A seller is trying to sell a house and to that accord anything to entice other parties would be within thier right. It really comes down to good marketing, your job is to make your house the most desireable to agents (to get more showings) and to buyers. The ethics of the buyer's agent however is a little different. As long as that agent is not placing thier desire for a larger commission above the needs of their sellers, they should be okay.
Neither state law, nor the Realtors code of Ethics specifically prohibits a seller from offering a buyer's agent bonus.
In the end you might be better served to reduce your price by $2,000 because the buyer is the one who ultimately makes the decisions and money in their pockets go much further than money in their agent's pocket.