buying an expired domain if its just the normal cost of $15 or less is usually a no brainier
the key to making this work is looking at what is already indexed in the search engines and what is already being linked too.
a handy tool to use for this is our domain tool http://simplesitesbigprofits.com/tools/domaintools.php
you can go thru the indexed pages, find out what there is and have someone set up a page for each one.
another good place to start is the https://archive.org/web/
way back machine tool... this will show you what the site used to look like and what the visitors will be expecting.
then you can put live chat on the pages and see if any traffic comes in http://www.providesupport.com/partner/simplesites
if the site looks good this can work really really well... and you can capitalize on existing page rank and backlinks
as for landing pages and stuff... make content that makes sense with WHY they are coming there. then decide.