Lets forget about the money for a second..
You need to sit down and work out what games you want, and then fill the rest of the container with games you don't want, but hope to sell. You will need to work on the games you want to sell. So there's your first hidden cost. Then you need to price the machines and sell the games. If you a reasonable tech, you can get them going, but you will be competing with established private sellers and dealers. Once you work out that it IS a lot of hard work, you may lose interest - suddenly it becomes a chore. You will need return on investment, so the pressure is now on.. Still - Not discussing money yet. You find missing components - sometimes entire assemblies. Ramps are 75% not presentable. displays often appear good in pictures, but then "in person" they are missing lines or outgassed.
That's EXACTLY the way I like them - but I'm set up for that - so it is very rare for me to view a game and consider it a "basket case".
Back to the money - what are you looking for ? DMD games ? Start saving $60 - $80K. Then freight, insurance, payment (sending 10's of thousands overseas..) - Flights and accommodation, maybe pack them yourself. Then pay GST, import costs and all the other costs and you can have your "Container Day" - which is the BEST day(s) of the year ! Be prepared to spend anywhere from $10,000 - $20,000 on parts (depending on your standards). Put insane hours into restoring the games.
It is not "doom and gloom" - it is the reality. I love sharing "Container Day" threads. I love seeing friends and customers turn up to check out their games. But what I don't show is the bank balance, the hours I put in organizing a container, the hours restoring each game - which you HAVE TO love doing. It is a lot of money sitting there and a slow recoup of the investment.
Rarely will you find the games you want in the same place, in the right condition, at the right time and the price you want to pay. If you have a LOT of money available to tie up in a container, and you are willing to work long hard hours finding parts etc etc - then by all means do it. There's no "big secret" other than you need to be patient and work hard. It took me 10 years to find some suppliers, and some suppliers are on ebay. You just need to look.
For the record - I have heard of friends sharing a container several times. Suffice to say they don't stay friends after Container Day.