This mod intends to do the same thing that UpcraftLP and nerdhubmc's Anvil Fix does in a non hacky way. I made it because that mod has issues with Ender IO's upgrade recipes.
What this mod does, essentially, is modify the way the vanilla anvil logic is performed in order to completely negate the increase in the repair/enchantment cost for repaired items, and also remove the level cap on the anvil, so that repairs or enchantments at level 40 or higher can be performed.
It has a couple of issues, due to the nature of it not being hacky and using established Forge methods - it doesn't allow creative mode players to apply invalid enchantments to items (like feather falling on a stick, for example), and it doesn't affect some modded anvils such as the OpenBlocks Auto Anvil and maybe others. It should work with the Ender IO Dark Steel Anvil, as it uses the same vanilla logic, however I have not tested it.
Credits to Shadows_Of_Fire for the amazing logo.