Rita, I know you're not trying to take it down that angle but, if one were to take it down that angle, one would have to account for the added intensity of the 5K. Personally, I always say every race distance is just as hard if you're running it to your full potential.
Andrew, the marathon is definitely an interesting event and I would strongly encourage people who are ready for it to give it a shot. That said, over the years, I've seen quite a few people who have run more marathons than races of any other distance and they have no appreciation for those other distances. Maybe if they ran them a few times, they could learn how great those distances are and they would show a little more respect for the distances and those who compete in them.
As for entry fees, most of them around here are still in the $20 range and you can still find bargains in the $10 range if you know where to look. Even the cheapest marathons I've seen are still running 3-4 times the normal for this area. Given that, in my opinion, it's the marathons that are gouging. Then again, maybe it's that East Coast inflation and East Coasters spreading their inflation through the marathon distance by traveling around the country to run what they consider to be inexpensive marathons. 😉