Leviton also made a line of X10 compatible products. I would expect someone will give you more information on them.
Yes, Leviton had their own line of X10 compatible products that they called "DHC". They offered both re-branded X10 products, like the in-line modules, and their own true rocker action wall switches. They did make a 2-way wall switch, which was the HXM10-1TW. It is a 1000W dimmer with a LED bar showing the brightness setting. Then they also made a transmitter only, which was the HCC10-1SW. As I recall, the 2-way dimmer cost $80 and the transmitter $40.
I installed the transmitter outside our media room to control the lights and switched outlets to power off the subwoofers and electronics rack when we were not using the room to eliminate a bunch of wasted standby power.
I did a Google search for the HXM10-1TW, and one popped up on "Smart Home Products" for $70.20.
Jeff