It could be an aerial mapping lens, but there isn't much call for those to be f/4.5 since they're generally shooting stuff under Sunny-16 conditions.

As to the price, it could be part of a money-laundering operation. Crappy old lens (unusual or obfuscated enough that it's hard to argue its real market value) goes one way, big sack of cash goes the other and the eBay transaction legitimises