are you planning to be a hardcore collector, very rare items, (rolls royce of portable console from 90's pc engine LT HK$5000-HK$10000) to extremely rare, limited aspect in gaming wise, very colllectible items (pc engine ld rom HK$3000-HK$8000, pc engine shuttle or pc engine super grafx, this is not so rare, around HK$800-1000), even to certain extent, super rare and expensive, but dodgy playaibilty games (circus lido, renny blaster, Tanjou Gekitouhen can be up to US$200-400 each etc)
or a nostagical type of collector of highly playable games (slight pricey) castlevania rondo of blood around HK$600-HK$900 here, magical chase HK$600-HK$1000, coryoon HK$500-800, ginga fukei sapphire HK$1,300 - HK$2000.
personally, the pc engine duo, best of both worlds with an arcard card, allows you to play 99% of pc engine games (but not compatible with supergrafx, ld rom or odd game altered beasr cd rom ver)