Complex sentence: GIFT was advertised to be a "GIFT to the fans" by the group themselves, so in result the three singles were sold at a special price of 888 yen and were a limited press release.
Split into simpler sentences: GIFT was advertised to be a "GIFT" from the group members to their fans. As a result the three singles were sold at a special price of 888 yen and were a limited press release.