Found two local stores that carry it by the gallon, I'm restoring a Civil War era book press that needs immersion so I ordered a 5 gallon bucket. Here's what I found so far.
Local dealerships that carry it in store:
Harbor Freight- Evapo-Rust? 1 Gallon- Item #96431 $21.99
Tractor Supply Store- 1 Gallon, SKU Number:1340932 - $21.99
Online order: Northern Tool- 5-Gallon, Item #334501 ?
$79.99 w/shipping $29.26 @$109.25 or 21.85/Gallon.
We lost our local area ACE Hardware I had to order my LPS3 online
