In this section, I'll post GateKeeper goods and where they can be bought. Below are list of links where you can buy some GK Merchandise:

Hikari's Anime Distribution - has Fansubbed GK Episodes 1 to 6
Saeba, Inc. - GK Episodes 1 to 3 and 3 TV Soundtracks as well.
CDJAPAN's GateKeepers Listing - has complete list of soundtracks, dramas, DVDs and VHS!

Here are lists of VHS, DVDs and CD Soundtracks sold in CDJAPAN.
NOTE: CDJAPAN HAS ORIGINAL MERCHANDISE AND ARE ALL IN JAPANESE LANGUAGE

GateKeepers VHS GateKeepers Vol. 1 Vol. 1 (ep 1-3) Animation, VHS (1), Released: 09/25/2000, BES-2632 ¥6300 / $52.25 GateKeepers Vol. 2 Vol. 2 (ep 4-6) Animation, VHS (1), Released: 10/25/2000, BES-2633 ¥6300 / $52.25 GateKeepers Vol. 3 (ep 7-9) Animation, VHS (1), Released: 11/25/2000, BES-2634 ¥6300 / $52.25 GateKeepers Vol. 4 (ep 10-12) Animation, VHS (1), Released: 12/21/2000, BES-2635 ¥6300 / $52.25 GateKeepers Vol. 5 (ep 13-15) Animation, VHS (1), Released: 01/25/2001, BES-2636 ¥6300 / $52.25 GateKeepers Vol. 6 (ep 16-18) Animation, VHS (1), Released: 02/25/2001, BES-2685 ¥6300 / $52.25 GateKeepers Vol. 7 (ep 19-21) Animation, VHS (1), Released: 03/25/2001, BES-2686 ¥6300 / $52.25 GateKeepers Vol. 8 (last) (ep 22-24) Animation, VHS (1), Released: 04/25/2001, BES-2687 ¥6300 / $52.25 GateKeepers DVD GateKeepers Vol. 1 Vol. 1 (ep 1-3) Animation, DVD (1), Released: 09/25/2000, BCBA-593 ¥6300 / $52.25 GateKeepers Vol. 2 (ep 4-6) Animation, DVD (1), Released: 10/25/2000, BCBA-594 ¥6300 / $52.25 GateKeepers Vol. 3 (ep 7-9) Animation, DVD (1), Released: 11/25/2000, BCBA-595 ¥6300 / $52.25 GateKeepers Vol. 4 (ep 10-12) Animation, DVD (1), Released: 12/21/2000, BCBA-596 ¥6300 / $52.25 GateKeepers Vol. 5 (ep 13-15) Animation, DVD (1), Released: 01/25/2001, BCBA-597 ¥6300 / $52.25 GateKeepers Vol. 6 (ep 16-18) Animation, DVD (1), Released: 02/25/2001, BCBA-621 ¥6300 / $52.25 GateKeepers Vol. 7 (ep 19-21) Animation, DVD (1), Released: 03/25/2001, BCBA-622 ¥6300 / $52.25 GateKeepers Vol. 8 (Last) (ep 21-24) Animation, DVD (1), Released: 10/25/2000, BCBA-623 ¥6300 / $52.25 GateKeepers Soundtrack and Drama GateKeepers 1970 Game Music, CD (1), Released: 12/17/1999, PCDG-110 ¥3150 / $26.12 GateKeepers Song Album Game Music, CD (1), Released: 12/17/1999, PCCG-514 ¥3150 / $26.12 GateKeepers Soundtrack Game Soundtrack, CD (1), Released: 01/19/2000, PCCG-522 ¥2940 / $24.38 GateKeepers Drama CD Vol. 1 Radio Drama, CD (1), Released: 02/17/2000, PCCG-525 ¥2940 / $24.38 GateKeepers Drama CD Vol. 2 Radio Drama, CD (1), Released: 03/15/2000, PCCG-528 ¥2940 / $24.38 GateKeepers Soundtracks Vol. 1 Animation Soundtrack, CD (1), Released: 7/19/2000, PCCG-540 ¥2940 / $24.38 GateKeepers TV Vocal Album Animation Vocal Album, CD (1), Released: 09/06/2000, PCCG-549 ¥3150 / $26.12 GateKeepers Soundtracks Vol. 2 Animation Soundtrack, CD (1), Released: 11/15/2000, PCCG-552 ¥2940 / $24.38 GateKeepers Opening Theme Animation Soundtrack, CD (1), Released:  PCDG-00119 NOTE: I haven't seen this on CDJAPAN's list, just got this info from the Official GK Site. ¥1,000