AC/DC power supplies with switching frequency synchronization

[radar_macgyver]

I'm looking for an AC/DC power supply that offers synchronization to an external frequency source. This seems like an option that's offered on DC/DC converter chips (eg: the LT8614 has a SYNC input). Has anyone has come across a similar option on off-line switchers? The only example I've found so far is the Artesyn iMP series. These are nice supplies, but have way too many bells and whistles and is too expensive for my application. Output voltages are 6V, 15V and -15V, current draws of a few amps per rail. Thanks.