“If i would get a bachelor degree here in Belgium, would i be able to get another one in the U.S?”
If you get a bachelor’s degree in Belgium, or in any one of a great many universities in Europe, Australia, the US, or Canada, then you can get a master’s degree in the US (or …). A master’s degree is generally more focused on your major, more technically advanced, and takes a lot less time (usually either one year or two years). The “less time” may correspond to less cost also. I have known quite a few people who have gotten a bachelor’s degree in one country and a master’s (or less often PhD) in a different country (often the US).
“Maybe like 50.000$ - 90.000$?”
If this is your total budget for four years, finding a university in the US could be a challenge. There are a few universities in Canada which would cost about $90,000 or $100,000 in US dollars (noting the dollar conversion rate) for four years, but the best known ones would be more expensive. I am not sure about universities in Australia. Europe might be more economical for you, but I expect that you know European prices better than most of us.
Regarding immigration to the US: You should be aware that immigration is a political issue in the US (and apparently in some other countries). What the laws are now might still be the same in 5 or 8 years, or might not. I personally find it somewhat difficult to predict what future US politics will do to US immigration laws. It is hard enough to guess what future US politics might do to the economy or anything else.