If you collect something whch is " special " / unusual, then you'd best include the names , addresses, and phone numbers ( where aplicable ) of true , acknowledged EXPERTS in the field , on your list. The government auditors / apraisors, of estates, are going to put THE highest price on EVERYTHING you leave behind, BUT, and you knew there was going to be a " but " , often they don't have any idea what they are looking at.
Now, you are handed a tax bill, and / or you've come into posession of X , you know what the government apraisor has claimed it's worth, but is it and IF you want to sell it / insure it, who do you trust ? Right now, IF you collect coins , be aware that MOST coin dealers are NOT trustworthy.
If you collect trains, yes, you CAN go to Christies or Southbys . They will NOT be happy to apraise your collection if you aren't going to auction off your things; however , they WILL do so, if they are affiliated with /a part of your estate planner's organization. The HEAD of Christies' antique toy department, is a VERY nice, knowledgable man ; however , he is headquartered at their home base ( LONDON ) , and knows much more about European trains, than American made ones. You will also have to pay the auction house a cut, IF and when you / your heirs put up the collection for sale. Another caveat ... MOST train auction houses in American , or the dealers in the back of train magazines are NOT trustwrthy ! Know who you are dealing with , and make certain that your heirs do as well.
Some collections ( such as antique musical instruents ) are in such a heady field, that you are going to have problems, UNLESS you know the one, or two American experts in this field.
Now, IF you are planning on leaving anything to a museum / historical society TELL THEM , after you have made up your Will, and DO follow that up, with a dated letter of intent. Make certain that they REALLY will want wqhatever it is that YOU want to give them. : - )