Anna, I'll offer my condolences on the passing on your father. You certainly picked the best place to ask this question. Everyone above gave excellent answers that you can go through to suit your purpose. Dereck with Stoudt is a longtime friend of many of us within this group, and can give great guidance. The business MikeCT gave is very reputable as well.
As someone who once helped a local woman in a similar situation with a nice American Flyer collection, I can say along with others you will need to inventory what you have as best as you are able. That is every locomotive, car, complete boxed set, accessory, etc. Part numbers will help a lot if your father saved the boxes. Yes, condition of each item matters too.
Please ask any questions here, and yes I agree, you can edit your initial post to remove your email address. You have it in your profile, and only logged in forum members can see that. I did the same thing as you when I first joined the Forum long ago.
