Go with serpent as I know most of the racers in Hong Kong play serpent and you can get setup sopport from Christopher(Wing jet).
Yeah if you know him really well by spending megabucks in his shop....
Well crunch, if you are going to play 1/8 in HK, your only choice would be either the Serpent or the Kyosho. The only 1/8 track here is ACO, and they would make you feel like an outcast if you drive a MRX3. Costwise Serpent parts are expensive, so I would suggest if possible get yourselves a Kyosho Evolva. The price of just one a-arm of Serpent = a whole tree of Kyosho Evolva parts... go figure for yourselves!
I don't think you can easily get either the Serpent 950R or the Evolva used in Hong Kong, as actually there are not many 1/8 running. However, why get used when the price of a 1/8 kit is about the same as an upgraded 1/10 TC? Also, you could at least get some support from the shop you bought the car from. If you get used, you are on your own...Then again, the most expensive element on running 1/8 is not the chassis of even that killer engine, but parts, tires and fuel.