Here are just a few websites that I have found that have info to help you finish your 80% lower if you decide to order one from www.FealtyArms.com
Here is a website that you can get the majority if not all of the tooling that you will need to complete the job. I will say that it is best if you order multiple lowers to spread the cost of the tooling between them, yes the Jigs aren't cheap but you are having the lower shipped directly to you so there is no dealing with an FFL.
Here is a good tutorial for doing the 80% lowers, like with any other firearms build it is important to take your time, read and re read the instructions, and be patient while doing the work. Taking your time will make a big difference in the quality of the end product that you are making.
And of course Monderno did a great write up with a video attached to it also, I highly suggest to head over there and check it out.