I wrote up a bit of a review of the YN-465 as a budget slave flash option for the YN-622C. Its not perfect but for around $60 shipped its hard to complain considering what it can do -
http://flashhavoc.com …-slave-flash-for-yn-622c/
IMAGE LINK: http://www.flickr.com/photos/flashhavoc/8126948041/
I don't have a lot of experience with the cheaper YN flashes so if I've got anything wrong, or you know of any compatibility issues please let me know.
Otherwise there is a YN560EX
slave flash for use with the Canon optic wirelss system, but nothing similar for the YN-622C.
Whats needed is ideally a YN-560-
SLV, an updated version of the manual YN-560 but with added ETTL and Remote Manual compatibility when used as a Slave with the YN-622C receiver. Preferably - Full power, Battery Port, Zoom Head, in about that order of priority, under the $100 mark.
IMAGE LINK: http://www.flickr.com/photos/flashhavoc/8126974244/
I don't mind the black screen but if you wanted the LCD look I think they could make a nice grey panel to look just like an LCD but actually using the YN-560 LED lights instead -
IMAGE LINK: http://www.flickr.com/photos/flashhavoc/8126947579/
If you would like to see a basic (but full power) sub $100 YN-622C slave flash like this, could you please leave a comment on the blog here and I will forward this to YongNuo to see what they can do -
http://flashhavoc.com/budget-slave-f...22_Slave_Flash
.