Also take a look at Kanardia gauges. I have the Combo, which is an electronic analog outer scale (and also stops at 20 mph - yes, disconcerting at first) but includes digital ASI as well as Alt in the center.
To be fair, this is my second one because the central screen on the first one stopped working within two hours but the new one appears to be stable. It is a nice setup and backup.
Correction since first posted: the center screen shows Alt and VSI - not digital ASI.
/Ed