Hi Beans:
The Redsun RP2100 is the version made and sold within China. Universal-Radio (As well as Kaito USA) will be selling a Kaito KA2100, which is basically a North American, rebranded version of the same radio.
Another point about this radio is that a newer version, called the Redsun RP3000, is expected soon (within calendar year 2007 I guess). It will include a numeric keypad for direct frequency entry, SSB (single sideband-- useful for hearing ham radio communications, utility stations, and clandestine broadcasts), and possibly synchronous detection (a feature for AM/SW radio that can reduce fading and interference). Radiointel.com is a website that is tracking the progress of the RP3000.
I have purchased multiple items from both liypn and tquchina on eBay and all of the transactions have been perfect. I would say the only differences between them is which radios they have listed/available, and that tquchina seems more friendly/chatty to me.
Good luck with your purchase!