1) If it is being done by a commercial estate sale company, they do not normally take any questions and definitely will not give out prices ahead of time. If it is being run by someone personally, such as family then you can have a good shot at an answer. 2) It isn't that common and pricing should reflect that it is an "as is" "where is" sale. As noted, it isn't usually that feasible. And as suggested, if you show up with the gear to test you may be able to plug it in and see how it goes but the time that takes anything else you are interested in may be snagged. If someone is with you, make a pile for them to guard, then test after the initial snagging frenzy.