Thanks to Aired, the regrade values for weapons have already been posted here.

I have been in the process of updating my previous spreadsheet for Patch 3.5 to reflect the new Patch 4.5 regrade values.

This is my Patch 4.5 spreadsheet for regrade costs:
The first tab is my results table. The black values are actual values. The blue values are my estimates. All other tabs are my sources for actual Patch 4.5 values and my estimation method using Patch 3.5 values.

Normal Weapons
Normal Weapons.png

Obsidian Weapons
Obsidian Weapons.png

Normal Armors
Normal Armors.png

Obsidian Armors
Obsidian Armors.png

My current estimates are based on a calculated percent (%) reduction for each weapon and armor grade. I took the known Patch 4.5 values and divided them by the Patch 3.5 values to obtain the percent reduction for each Tier and Grade. I then found the average percent reduction at each Grade for All Weapons and All Armors. I used this averaged percent reduction to predict the Patch 4.5 values based on the Patch 3.5 values. You can see my derived percentages in the "% Change in Regrade Fees" tab of the worksheet.

I verified that my estimated values were accurate based on Aired's weapon values that he found on the PTS and through my armor crafting on live. I am confident that my estimated values are close (3.5% variation or less on sampled values) to the actual regrade values.

Previous Work
Patch 3.5 Regrade Sheet
Patch 3.5 Regrade Sheet Forum Post

Related Works
Aired's Patch 4.5 Weapon Regrade Values
Aired's video explanation