I've bought from Puretime, Marvellous Replica and Timeshops. All good on all transactions. Some have stuff that others don't. Make sure you ask for the latest and study the QC pics closely to make sure your He valve is in the right place, that the Omega symbol is straight and not the one with 'happy feet'.
Probably find one as the 'best', 'ultimate' or '5th gen' as these will have a superclone of the ETA 2824 movement and they are pretty damn good.