If it's too cheap Bungie will never go for it. It's not about what's reasonable, it's about what will work within the confines of how this game operates. This game is about grinding, therefore any suggestion has to have a grinding at its core. Your idea is too cheap.

No the max to glimmer is 25000, meaning that you could only get 5 etheric lights for about a week or even less.

There is no weekly limit on glimmer, only what you can carry at a time. I can farm 25K worth of glimmer in about an hour or so on Venus. Your idea would flood the market making Etheric Light making it useless. Bungie would never go for this.