A little bit of basic house keeping is in order. First item is that you are going to be in process of liquidating assets. You have to identify and define the markets that you have access to. The franchised dealers that may sell on commission are going to market their stuff first and yours only if a customer comes by that happens to need what you have. You might thing of this market as a retail market because there is no defined sell date.
The auctions are a secondary market and are always a liquidation market. The day of the auction, the machine sells unless you put a reserve value that must be exceeded by bidders. Most of the auctions have gone to no reserves now so if no one wants the item, it may sell for next to nothing.
Private sales are also liquidations but you have a direct contact with the seller and have to handle all the functions of the sale. You have to do your research first on finding the liquidation market ranges that each piece might bring. Then you have to advertise it and deal with the potential buyers who will want to negotiate price. Something like the backhoe you show will have a lot of negotiations if priced high and you will have to have some thick skin in selling at a high rate. You see plenty of machines being offered on Craigs List, Ebay, Equipment Trader and so on.
Some other home work you will have to do is make a full list of each piece as suggest above. Second item is to make sure that each item is paid for. There should be paper somewhere showing any encumbrances on the fleet. Selling a machine and then finding out of an existing loan balance or a lien against all the iron would leave a buyer in a very bad mood and you in possible legal jeopardy. There should be a bill of sale somewhere for each piece.
As for values, all the above is good advise. You might also check to see if there was any insurance that might have replacement costs. Another place to check is with the banker who financed the iron to start with. They might have access to people who could provide you with a desk top assessment of what you have. If you have not been part of the industry, I would generally advise you to work with a professional. That might mean a consignment to a local dealer that may or may not have a franchise with a major manufacturer. I do have a short book on Amazon that explains some of the process that one goes through to buy and sell equipment. You can preview it on the following link. Good Luck!
http://www.amazon.com/dp/B073ZXGQNJ