Jugen, I have two machines. My Singer Dressmaker will handle 4 layers of denim and has a lot of useful stitches, free arm and built-in buttonholer. I bought it at one of those sales of undelivered school machines. They have these sales, all over the place. Look for ads, in the newspaper. I paid $150.00, 10 years ago. Its never needed a repair, just a yearly tuneup.
If you want to go a bit higher, I, also have a Euro-Pro 7-layer machine. Does all of the good stuff, too. My ex bought it from Fingerhut for around $250.00.
If there's a fabric store, near you, they may sell reconditioned machines, too. I've always had good luck with Singer, though.