You can get a complete AR-15 from PSA for $370 during their black Friday sale. Shipping is showing $17 for me, so $387 out the door plus FFL transfer fee at your local dealer. This is the budget PTAC line. If you spend a bit more, you can get a bit more quality.
complete lower $119.99 shipped
http://palmettostatearmory.com/psa-pa15-blackhawk-complete-lower-receiver-blem.html
complete PTAC upper $249.99
http://palmettostatearmory.com/ptac-16-m4-1-7-upper-with-bolt-carrier-group-and-charging-handle.html
Add a couple 30 rd magazines for $6.99/each
http://palmettostatearmory.com/catalog/product/view/id/1239/
Since this is a lube forum, I highly recommend G96 synthetic gun oil.
http://www.amazon.com/Rothco-G96-Synthet...eywords=g96+clp
complete lower $119.99 shipped
http://palmettostatearmory.com/psa-pa15-blackhawk-complete-lower-receiver-blem.html
complete PTAC upper $249.99
http://palmettostatearmory.com/ptac-16-m4-1-7-upper-with-bolt-carrier-group-and-charging-handle.html
Add a couple 30 rd magazines for $6.99/each
http://palmettostatearmory.com/catalog/product/view/id/1239/
Since this is a lube forum, I highly recommend G96 synthetic gun oil.
http://www.amazon.com/Rothco-G96-Synthet...eywords=g96+clp