Sometimes you can stumble across a deal that is too good to be true.
For example, not to long ago one dealer was selling used Aimpoints, Eotechs, and ACOGs very cheap. Aimpoints were running about 100-200 dollars including a Wilcox mount($90 MSRP), $300 dollar TA01NSN ACOGs and Eotech 553s.
Needless to say these were all used and abused military equipment. But we don’t know if these were legitimately surplus of if they “fell off the truck”.
There are a few major issues with buying surplus optics. The first is that there is the chance it is stolen. If it is stolen, and there is an investigation, you have have to turn it back over to the government with out compensation.
The second is that if you have an issue with the optic, the manufacturer may not offer warranty or repair it. Companies like Aimpoint, Trijicon, and L3 do not have a way of knowing if an optic was stolen government property or if was properly surplussed out. Because of this, most of the time these companies will not service these optics.
I bring this up because Law-Guns were selling military Eotech 553s. Some people were buying these and sending them in to Eotech to be rebuilt. Finally Eotech said these are government property, and confiscated the ones sent it.