A friend just found a Litton m845 for around $500 trade wise. I don't know alot about the older Litton's, thanks to the forums & the wealth of info provided I should have a pretty good idea if its a keeper so to speak, but the total amount of use its seen will still be up in the air. Its a gamble & I am waiting to check the tube out when it gets in, if nothing else it will be interesting to compare an older gen2 with much newer Gen 3 tubes. Luck may be on his side or he may just end up sending it back. His intended use will be coyotes with an AR-15, so I'm fairly sure the Litton will be worthwhile as long as it passes inspection. Keep your eyes peeled, ask questions, & you just may find a great deal - but be cautious & use this forum to guide you. Used equipment such as this requires research & friends who know more than you do...