Nobody could ever argue that a DIY kit should cost less since I figure the cost of the kit is only known by the developer of the mod. So then, Yurkie could sell his mods the amount he invests in each and every one of them, even more! No need to do anybody a favor by selling cheaper, he's the mastermind behind all this.
Go on Yurkie, DO sell DIY kits, but please sell at the price YOU judge fair and that will allow you to get the money you deserve! Anyways, if people that want to install their own DIY kits would of paid the mod anyway if they had to get it done by you, might as well pay full price for the kit too, they don't have labor cost to consider, it's their own time!
The only way I could see this backfiring is if someone else would build and sell these DIY kits for cheaper.