I've come back into the game while waiting for other games. There are sooo many other good games and less and less time. I didn't find a great monetary calculation by anyone out there that was up-to-date so I created my own spreadsheet and did some calculations on the new Thieves Guild, Orsinium and Imperial City expansions.
There are all purely crown only calculations based on cost per crown with today's crown rates and bundles. March 8th, 2016 - in US Dollars.
As of today, the prices in crowns are:
1. Imperial City - 2500 Crowns
2. Orsinium - 3000 Crowns
3. Thieves - 2000 Crowns
Current prices for crowns are on discount according to an email newsletter.
750 - $5.99
1500 - $11.24
3000 - $16.74
5500 - $23.99
If I were calculating solely on cost per crown buying the bundles, here is how much the entire set of DLC (7500) would cost.
750 pack - $59.90
1500 pack - $56.20
3000 pack - $41.85
5500 pack - $32.71
If purchased with the crowns included with an ESO Plus membership
1 month - $74.95
3 month - $69.95
6 month - $64.95
(but you would get the other benefits of all of ESO Plus)
So in my circumstance, since I will be on/off again with the game as new ones I want to play be released, I'm going with the 5500 crown package x 2 = 11000 Crowns for $47.98. That leaves me with 3500 crowns left which I only paid $15.32 for... saving for future expansions or other in-game crown goodies.
I hope this was helpful to someone out there that hasn't purchased any DLC content yet.