graz posted:These are the 12v AC Ice-cube style relays that I use for my signals.
https://www.automationdirect.c...,_plug-in,_3a_-_15a_(78x-z-_qxx-z-h78x_series)/general_purpose,_15a_(781_-z-_782_-z-_783_-z-_784_series)/782-2c-12a
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Your link dropped some characters so gives and error. In any case I put the following together from their website with what I believe are the 12V AC relays and sockets you refer:
So $8.75 for a 12V AC SPDT (15A contacts) and socket. $9.75 for a DPDT version and socket. The DPDT version means one relay can handle both the hi-current block power switching (on one pole) and the low-current signal switching (on other pole). Orders of $49 gets you "free" domestic shipping so these would come much faster than anything from eBay-Asia.
These relays have a built-in LED indicator as well as a push-to-test button. Nice! 
I wonder though if 12V AC is available as an Accessory AC voltage for the typical layout. A layout train transformer might only have only a fixed AC Accessory output such as 14V or 16V AC. Or there may not be a spare throttle that can be dialed down to 12V AC and dedicated to powering relays. The spec sheet says the maximum coil voltage should not exceed 110% or 13.2V AC for relay power.
Also, I have not experimented with AC-coil relays with respect to contact-bounce or chatter from dirty/intermittent wheel-to-track contact. The DC-coil approach allows application of inexpensive capacitors for DC energy storage to demote relay chatter.
