It's true the DBMS_RANDOM package doesn't offer any range-base generator, its RANDOM function only return random *******s in the range of BINARY_INTEGER, which means between -2**31 .. 2**31. But it is very trivial to get only values from a specified range. For example, if you wan't to get random positive integers in the range between 100 and 199 you would use something like:

100+ABS(MOD(dbms_random.random,100))

HTH,