For those kinds of 3rd parties I'd probably look in Sino. I haven't been into Ins Point recently but it didn't have much even the last I was there. Similarly aside from the Toy Hunters shop in CDMA I don't think you'll find much 3rd party TF's. I wouldn't even bother with Superman Toys as they haven't had Transformers other than the bearbricks for well over 6 months (and they're really rude - especially to this short fat non-chinese chick).
As I mentioned earlier - for the new/recent/modern Tak-Tomy and Hasbro stuff - walk the toy shops in Wan Chai market with particular focus on Freeway Toys (the first shop on the left as you enter the markets from the Tram/MTR but expensive) and the toy shop on the right further down that is right next to a toy shop loaded with cars (can't remember the name - keep thinking something Hing Toys but could be wrong). Also as I mentioned shop around BEFORE buying.
I was going to recommend a place near me for MP's but went there last night and unless you're after Soundwave his shop has sold out of everything - which is impressive given 2 days ago he had 10 MP Ultra Magnus' in stock along with Smokescreen, Prowl and a few others filling one of his glass displays.
Good luck with your hunting!