Personally, I'd stay away from bottom of the barrel stuff. And, maybe consider getting one with a decent trigger if you can swing it. Several website allow you to 'build your own" LPK.
Example:
Choose only the LPK parts that you want and don't waste money on parts that you're going to replace! You can build a Geissele Lower Parts kit, a Magpul MOE LPK or a lower kit with extended take down pins. The options are endless!
www.righttobear.com
For a basic kit: I have had good luck with the CMMG. Color coded baggies help and quality parts.
I have never retained a milspec trigger or grip. Actually, I end up changing most stuff so I order each part separately. Just my opinion.