The kit on ebay has most of the items. They claim All parts are either Genuine Honda, or OEA, OEM
Should I not trust them (FCP Groton, LLC) ?

 

$600 for a t-belt from a dealer is really not that much. ask your brother if he had the seals replaced during the first time that the belts were changed. also honda recomends to replace your belts every 80k or 6 years. i work for a honda dealeship and i'll tell you this, i would pay more money, but i'll know that the job was done right. we change t-belts where i work on regular basis, and it comes very naturally now. it'll be done right, by a honda proffesional, and it will be done well. also get honda parts, they last longer.
my suggestion to you and to everyone else, where they don't make better aftermarket parts, go for factory!