Best Site To Buy Bulk Coins?

Forget ebay, shipping can cost you more than the the value.

Try coin dealers. They often have boxes or buckets with foreign coins that they sell by the pound or kg.

Not sure if you want only Europe coins, Asian coins or USA coins. Also, you could possibly want Canadian or Mexican coins. For one thing stick around here until you get 250 posts and then possibly buy some from members here. If you watch these posts frequently you will see coin dealers mentioned that are on line and by contacting them, they may have what you want or could use.
As noted already, stay away from ebay. There are numerous on line dealers that could possibly send you a lot of coins. Again, would depend on what country type of coins you want.

Not sure how things are today in Europe but about 15 years ago my Son went to school at the University of Krakow for a while. Sort of an exchange type program thing with his college here. He landed in Belgium and his class land traveled accross most of Europe to Poland. As he went he acquired coins and sent them to me. He never said anything to the postal people that there were coins in those letters and/or packages. Some people asked for USA coins and I sent him some the same way. No one ever opened them, none ever got stolen or lost. Things may be different today but back then it worked great. Might not be the right thing to do but if I were you, I'd do the same thing.

Nobody can help me?

You could try http://www.vcoins.com as not all the sellers come from the United States.

As already noted stick around here for a while until you accumulate 250 posts. Then you can deal with members here for coins.
One thing you could try too is go to the Search Tab at the top of the screen and type in coin dealers or coin dealerships or coin stores, etc. You should be able to accumulate a list of dealers here in the USA. Then by email, contact them as to getting you coins.