Originally Posted by
bgammill
Do you mean that the price for that departure day is lower, or do you mean the day you buy a ticket (tuesday, wednesday, saturday) may determine the price of the ticket?
While anything can happen, these tend to be less popular days to travel so fares tend to be lower. This isn't always true, but you can do your own test by checking fares on the same itinerary, a couple of months out, for a range of adjacent dates. Some booking sites make this easy by showing a fare grid for a range of departure and return dates around the date you request.