what i have found with PSA is that they will have a bargin sale. they last about 24 hours or so. you have to be quick with them. they will only offer up a few items for sale at a time, except for the lower receivers. they will have a few thousand of the and they sell very fast.
i have built several complete rifles for under $450. they are an easy build. i have not had any problem with any parts yet. the only thing i don't care for is they have there logo on everything that it will fit on.
i bought several complete extras for my grandsons to build when they get older. keep in mind if you buy a complete kit with lower you will have to pay a federal tax, so don't order everything at the same time.