I just built a 9mm AR (banless). I am very pleased with it and it runs 100%. No malfunctions of any kind! Here is what I did:
Rock River 9mm A2 upper - $480
Rock River Lower - $100
Parts to include lower kit, stock, grip - $75
VM Hytec block - $150
Total - $805
That leaves you about $200 for other goodies!