I bought a set here in Oz earlier this year. They were about $3 a piece against $18 from Agco (who did not have stock in Australia anyway). They were listed as a John Deere peg but are near enough to identical to the Allis part except for the thread. They supplied the nuts with them so that was not an issue. It's early days yet but they seem to be reasonable quality.
If you are here down under I can tell you where to look, otherwise check out your own after market suppliers.
I put some in an F2 a few years back and they were not near that high that would be over 1800 dollars to put spikes in an f2, and over 2000 to do a L combine. I may be wrong but I believe they were around $6 ea. about 7 years ago
Don't forget I'm in Australia, we pay near enough to double spare parts prices in the states.
$18 a piece was the quote from my local Agco dealer. If I wanted them inside 3 months they wanted another $420 for air freight.