My first Asian etaclone claimed to be swiss and with eta markings was from 'Paul' at Abay about 5 or 7 years ago...maybe longer. Paul said he did not know it was a clone and made it up in a later deal. After that I really slowed down buying replicas but a few friends did not so I have seen a lot of eta signed clones since then...all claimed to be "swiss" of course.
I guess it was about 5 years ago when they really hit the market in full force with a few actual 'swiss etas' thrown it now and then. Now, going from what I have seen and read there are very few actual swiss made etas showing up.
So I agree with mymanmatt when he says not to expect a swiss eta no matter what the seller says and if you do happen to get a swiss eta, do not expect it to be new or in top notch condition.
I do not know what qualifies as a 'keeper' but if I spotted one from a 'trusted whatever', I would go with the Asian eta clone and be prepared to buy a genuine swiss eta and have it c/o and install it in the watch later.
Buying a watch with an Asian '21 jewel' movement to save $$ is Ok unless you plan to install an eta movement later because the dial and hands will not fit on an eta. If you do swap the '21' out for an eta you will need a set of hands and will have to figure out a way to mount the dial without dial feet.
Basic '21 jewel' types used in many replicas...
Miyota clones
Seagull ST6 and ST16
The Seagull ST16 is a combination of Miyota clone and Seiko with a Miyota type movement and Seiko 'magic lever' type winding system. The ST6 is a model made from scratch in the 'traditional' design with the autowind assembly screwed on top of a basic hand wind movement. The ST6 is smaller than average but has an oversize top (dial side) plate to allow it to be used in regular watches.
I have had good luck with ST6 and ST16.
The ST16 is also souped up in switzerland and renamed the 'swiss made' Claro CL-888...it used to be called the Claro Semag CL-888.
www.clarowatch.com/movements.html