I've bought several things at RB auctions, some stuff from purple wave and iron planet also. If its a crane that I think is worth about $80,000, I don't want to give more than about $50,000 for it at a auction. That way I have the $ room to replace a engine, or a LMI computer, a new set of tires, or a rear axle assembly. I want a deal, and I want to be able to fix what's wrong with it and still have a deal. Or I'm not buying it.
I actually just bid on a crane at a rb auction in texas. I had a limit I was willing to spend, and it brought about $7,000 more than I was willing to give. If I would have been able to drive down there and look at it myself, I would have bid higher if the condition justified it. But without seeing it and running it, I've got a limit.
Cranes are typically a little different use than excavators/ dozers, they are usually not beat to pieces as bad, simply because of the work they do- less impact stresses. But if you bought a crane with a junk turntable bearing, you just bought scrap, because they are usually too cost prohibitive to replace.
I feel competent to inspect something myself that I'm looking to buy, but I'm willing to take my lumps if I get it wrong also. I usually figure whatever I buy for a crane, I'm going to spend $10-$15,000 on it in the first year to get it to what I feel is "operational" condition. To buy something at auction thinking "I can put it right to work" is foolish. If it was still perfect, they wouldn't be selling it.
I have also been able to buy some auxiliary equipment at really good prices on auction, but its stuff that is pretty specific use, that not everyone wants.