To start, look up the various brands that you have on these sites:
http://pipedia.org/wiki/Pipe_Brands_/_Makers
http://www.pipephil.eu/logos/en/index-en.html
Both of these sites are good places to get information about the pipes that you have.
If you have a B&M near you, bring in the pipes and see if the owner can help answer some questions, or maybe take some pieces on consignment.
Next you can try searching eBay for prices to get an idea.
http://www.ebay.com/sch/Pipes-/4118/i.html?_trkparms=65%253A12%257C66%253A3%257C39%253A1%257C72%253A4203&rt=nc&_sticky=1&_sop=10&_sc=1&_trksid=m194&ssPageName=STRK:MEFSRCHX:SRCH
What I would do is enter the brand name of a pipe in the search window, and then select the "Advanced" button to the right of the SEARCH button. Enter the brand name in the "Keyword" box, then check "completed listings" and finally click on "search", to see what a pipe of this type has gone for in auction.
You should be aware that make, model, and condition are all important factors in the value of an estate pipe. Not all pipes made by one specific manufacturer have the same value. Value can vary greatly on how collectible the pipe is.
Above all, be patient. It takes time and effort to understand estates, but it is worth the effort if you have some valuable pieces and want to collect on that value.