how do I find the value for sale for a macintosh SE and a laserweriter16/600
both purchased new have photos of serial#
Pricing varies hugely depending on country, and even within one country. Example: The town where I live has little Apple presence and used Macs are expensive. If I drive to the university town 40 miles away, they a ea cheaper.
I don't see much interest in either of your devices except to collectors; if you can find a Mac collectors site, that could be your best resource
Otherwise your best option for finding approximate local pricing (not I did not use "value") in your area are any classified ad sites that allow you to select a city or area. Craigslist is an example.
Auction sites like eBay represent the nation that the site serves so prices can be all over the place. Still the wide range of "buy it now" prices on eBay might be somewhat helpful.
I used to steer such questions to local Mac User Groups, but few seem to be a going concern any more.