1) The most common cause for traces of blood in urine is urinary tract infection.
2) The second commonest cause is stone disease in the tract; anywhere in kidney, ureter or bladder.
There are other uncommon causes too like glomerulonephritis (inflammation of the kidneys, which is essentially a medical disorder), tumors, etc.
But any blood in urine whether is macroscopic or microscopic (regardless of amount) is investigated thoroughly with ultrasound, intravenous pyelography, CT and nuclear scans. Read about hematuria (blood in urine);
Please feel free for your follow up questions.
If one goes step by step, probably the cost can be reduced. First investigation would be an ultrasound and 24 hours urine for albumin. If these tell the diagnosis, which would probably cost around 500 USD, the other investigations may not be required. But that will all dependent on your urologist and most of specialists are that way understanding.