Haven't tallied up receipts, honestly. I've been gathering parts here and there for a while now...
I'd guess someplace near $50
I already had the SJO cable, wire and a plug end lying around though.
The items I bought would be:
STC-1000 about $25
4x4x4 box $7
amber neon lamp $1.99
red neon lamp $1.99
1/8" mono panel mount jack $1.99
1/8" mono plug end $1.99
receptacle $2
cord restraint $2
terminal strips (2) $2
I did buy an IEC cable plug so I could use a computer cord to plug into it also, but decided that I didn't feel like cutting anymore square holes than I had to.
Ultimately I'm quite happy with the cord restraint I used, even with my OCD
For anyone looking to build this... I'd advise against using 12ga wire like I did. I used 12ga stranded and I had to thin it down some to get it into the STC-1000 terminals. I did tin all of the wire ends with solder though...
I might dig into it and do it all in 14ga at some point, but knowing me, if it's working and not ugly, I probably won't.