Craigslist Deal Finder integrates eBay prices into Craigslist. Stop trying to decide if the Craigslist item is reasonably priced and let this extension do the work. Craigslist Deal Finder provides average prices found on eBay for each Craigslist item on the page.
A list of the found eBay items can then be displayed by clicking the "eBay Price" button. This will display all the retrieved items and link them to the associated eBay web page.
If you're not getting the results you expect open up the search filter panel and modify it to fit your use case.