I'd probably do something like 100 silver per essence (chart for reference) to start with average skill.
Code:
+0 to +1 0
+1 to +2 100 = 10k
+2 to +3 200 = 20k
+3 to +4 300 = 30k
+4 to +5 400 = 40k
100,000 for 0x-1x
+5 to +6 500 = 50k
+6 to +7 600 = 60k
+7 to +8 700 = 70k
+8 to +9 800 = 80k
+9 to +10 900 =90k
350,000 for 1x-2x
+10 to +11 1000 = 100k
+11 to +12 1100 = 110k
+12 to +13 1200 = 120k
+13 to +14 1300 = 130k
+14 to +15 1400 = 140k
600,000 for 2x-3x
+15 to +16 1500 = 150k
+16 to +17 1600 = 160k
+17 to +18 1700 = 170k
+18 to +19 1800 = 180k
+19 to +20 1900 = 190k
850,000 for 3x-4x
+20 to +21 2000 = 200k
+21 to +22 2100 = 210k
+22 to +23 2200 = 220k
+23 to +24 2300 = 230k
+24 to +25 2400 = 240k
1,100,000 for 4x-5x
+25 to +26 4800 = 480k
+26 to +27 7200 = 720k
+27 to +28 9600 = 960k
+28 to +29 12000 = 1.2M
+29 to +30 14400 = 1.44M
4,800,000 for 5x-6x
+30 to +31 16800 = 1.68M
+31 to +32 19200 = 1.92M
+32 to +33 21600 = 2.16M
+33 to +34 24000 = 2.40M
+34 to +35 26400 = 2.64M
10,800,000 for 6x to 7x.
+35 to +36 28800 = 2.88M
+36 to +37 31200 = 3.12M
+37 to +38 33600 = 3.36M
+38 to +39 36000 = 3.60M
+39 to +40 38400 = 3.84M
16,800,000 for 7x-8x + potion costs
+40 to +41 40800 = 4.08M
+41 to +42 43200 = 4.32M
+42 to +43 45600 = 4.56M
+43 to +44 48000 = 4.80M
+44 to +45 50400 = 5.04M
22,800,000 for 8x-9x + potion costs
+45 to +46 52800 = 5.28M
+46 to +47 55200 = 5.52M
+47 to +48 57600 = 5.76M
+48 to +49 60000 = 6.00M
+49 to +50 62400 = 6.24M
28,800,000 for 9x-10x + potion costs
Might need some tweaking, but feels like the right level of conversion. Slightly more expensive than previous enchanting costs, but there's quite a bit more effort involved, and the higher end stuff could end up being less than previous depending on the cost of the new potions.
The other factor will be the difficulty of the item. Younger wizards may charge more like 50 silver per essence because they can't do difficult items or high enchants. Far post cap wizards who can enchant your most challenging items to 10x might be charging like 200 silver per essence.
Of course, at the rate I specified it would only be 1.6mil per wizard week, which isn't comparable to ensorcell, so I suspect wizards would be looking for more like 200 silver per which would be closer to ensorcell at 3.2mil per wizard week. Either way, I think pricing "per essence" is probably the easiest model to manage.