According to my research, in order be offered correctly Taps should be played "from an unseen distance" as experienced by those who are honoring the deceased. When playing for a funeral at the Presidio in San Francisco, I placed myself behind a large tree a few paces from the mourners and made sure to walk from the site keeping the tree between myself and the mourners.
It is proper for Taps to be performed live and in person at the grave site, and I recommend the following resources as possible avenues for finding a local trumpet player who can provide this service for a standard and reasonable fee. In fact, the musician's union has set rates for this service, though it might vary by region or locality. You may be able to find a professional trumpet player by calling one of the following organizations: The local musicians union (look in the Yellow Pages under "musicians"; A local orchestra (start with the box office or business office and explain your situation); A local university or college music department; A local high school music department (ask for a local trumpet teacher or a very talented high school player); Christian churches often use trumpet players for Easter and Christmas services, so the music director there may have a short list of players in the area. By the way, I'm not being exclusive here by mentioning only churches. I simply know of no common Jewish or Islamic services where professional trumpet players would be employed.
It is difficult to see to every detail of a memorial service in times of stress and loss. There might arise a occasion for which no qualified trumpet player (military or not) can be found. It is for these situations that I offer this resource, a high definition digital recording of a professional trumpet player performing Taps. I do this in honor of those who have served our country, and in sympathy with those they've left behind.
The link will take you to MP3 and WAV sound files, which is are the most common digital sound formats. You should be able to copy these files to a local drive and then burn them to an audio CD for playing at the grave site.
I would strongly suggest that you have the CD player carefully positioned so that the sound of Taps is heard clearly, but "from an unseen distance" as I would play it if I were there. Aside from being in compliance with the proper protocol for such occasions, this may also allow mourners to remain undistracted by the fact that it is a recording.
(Please note - May 25, 2003: The sound files are not quite ready to upload. I'm hoping to have them up by the end of Memorial Day. Then the links below will work.)