I am joining AROTC next year and want to get used to shooting and disassembling and reassembling a rifle close to the Army's M4. I've looked into buying one and everyone seems to say that building my own would be the best and the cheapest way of doing it. Is this true? Or I could buy the upper and lower assembly separate and put it together from there? I don't have too much money to spend and would like to be under $1000. If you have any suggestions or tips on where I go from here that would be great! Thanks a ton!