Make sure you are mechanically inclined if you are mail-ordering a bike (there is no warranty available as T-Motorsports is an importer, not an authorized American Lifan dealer who offer 6 month warranties).
As far as 300's--they seem not to be available here in the US as of yet, with 250's having a limited presence (and the presence limited to completely non-streeted dirt bikes). It will take awhile for the bigger enduros to make any inroads--the 200's are plenty available and cheap right now, so there is no hurry to bring anything bigger in, yet.