It’s basically impossible to now calculate the total DLC cost for Train Sim/FSX because they have so much DLC, and Steam won’t show the total for DLC once a game reaches 201+ DLC packs. I’ll keep the existing prices as seen in May 2020, with other games being updated. Sorry about this 
As of January 27, 2021, it would cost at least
$17,512.61 USD
(and it would cost at least $17,787.51 USD to buy all the DLC and the base games)
(Celebrating over $16k of DLC, and 4 years of keeping track of this!)
About:
One day, I had a great question. How much does it cost to buy all the DLC in Dovetail’s games? How much could you spend on virtual trains in Train Simulator? Why am I trying to make this site look better on SEO by using very specific wording?
And so, Dovetail’s DLC was born. Proudly keeping track of Dovetail’s ludicrous DLC for 4 years.
Price breakdown:
All prices are calculated from the US Steam Store when no sales were ongoing. Local prices may be higher (or lower).
Base game packages usually include DLC – so the price to buy all DLC & base games is not 100% accurate.
Note: Although Dovetail doesn’t publish FSX anymore, it’s still included in here since they contributed to the ludicrous amounts of DLC.
Flight Simulator X costs $24.99 USD for the Steam Edition
Train Simulator costs $29.99 USD for the Standard Edition
Train Sim World 2020 costs $29.99 USD for the Standard Edition
Train Sim World 2 costs $29.99 USD for the Standard Edition
The Count of Monster Disco costs $9.99 USD
Euro Fishing costs $19.99 USD
Fishing Sim World: Pro Tour costs $19.99 USD
Great British Railway Journeys costs $44.99 USD
The Catch: Carp and Coarse costs $24.99 USD
Fishing Sim World: Bass Pro Shops Edition costs $39.99 USD
Flight Simulator X has $5,355.22 USD of DLC (Last update – 5/1/2020)
Train Simulator has $10,419.22 USD of DLC (Last update – 5/1/2020)
Train Sim World 2020 has $644.74 USD of DLC
Train Sim World 2 has $759.70 of DLC.
The Count of Monster Disco has no DLC.
Euro Fishing has $122.91 USD of DLC
Fishing Sim World: Pro Tour has $192.84 USD of DLC.
Great British Railway Journeys has no DLC.
The Catch: Carp and Coarse has $17.98 USD of DLC.
Fishing Sim World: Bass Pro Shops Edition has no DLC.
Price History (all in USD):
March 12, 2016: $7,060.46 DLC, $7,135.43 DLC + base games
April 25, 2016: $7,252.42 DLC, $7,327.39 DLC + base games
August 9, 2016: $7,835.54 DLC, $7,925.50 DLC + base games
February 4, 2017: $8,909.11 DLC, $9,084.04 DLC + base games
August 12, 2018: $13,218.58 DLC, $13.365.54 DLC + base games
December 15, 2018: $13,926.10 DLC, $14,063.06 DLC + base games
February 12, 2019: $14,093.99 DLC, $14,270.94 DLC + base games
May 2, 2019: $14,443.89 DLC, $14.598.83 DLC + base games
June 16, 2019: $14,707.74 DLC, $14,842.68 DLC + base games
October 14, 2019: $15,497.43 DLC, $15,632.37 DLC + base games
May 1, 2020: $16,679.96 DLC, $16,859.89 DLC + base games
January 27, 2021: at least $17,512.61 DLC, at least $17,787.51 DLC + base games
Why?
The world needed to know how much Dovetail loves DLC. Updated manually every 2-4 months.
