For your AR, what is your purpose for it/intended use?
How much are you able to spend on the rifle alone (no optics)?
What is your optics or sight budget?
Spikes is a good place to start for a lower. $115 for an over-the-counter price is fair, and you're getting good quality.
If you can't afford anything better, then go ahead and try the PSA; though I would make sure to do a thorough inspection with their products. They have not been vetted in the tactical shooting arena like other companies like Spikes, Daniel Defense, Rock River Arms, CMT/Stag, etc. If you can afford better, I would spend for better. Don't cut costs for the sake of just cutting costs. Of the areas where you can save money, the lower parts kit (LPK) is not one of those places where you should try to cut corners (the others being bolt carrier group, lower and upper receivers). Companies that have proven track records of good quality control (QC) are the ones you should buy from. PSA is still new, and I would just assume let others be the test guinea pigs to determine the quality and reliability of the parts. I have seen a PSA lower take a massive dump on the range, so my personal opinion of them is not particularly high at this time and won't be until I start to see some more positive evidence of their quality. Personally, I'd put in a Spikes or Daniel Defense LPK. I'd much rather have an A2 pistol grip with a quality LPK, than a Magpul or other aftermarket grip at the expense of having to install a LPK from an unproven company. While there are deals to be had out there, most AR parts and accessories have a quality commensurate with their cost. You get what you pay for, and the phrase "buy once, cry once" really holds true.