I need help picking out some upper components. I have a Frontier Arms Glock Lower. This rifle will be a plinking gun don't really care for accuracy... just reliability.

I see DaytonaTactical having regular sales on 16" 9mm Barrels for like 70-80$

I currently have a Blem Spikes Upper that I paid little to nothing for.

I have a standard LPK for an AR15, and the Lower

I have an old quad rail w/ barrel nut...

What's the cheapest bolt carrier I can get for 9mm that's compatible with glock style mags?
Also, what other components will have to add to my standard LPK to be reliable and not break bolt catches?

Spinta precision has a 16" stainless bead blasted barrel if you don't mind 1/16 twist and 1/2x36 threaded muzzle $85
http://www.spintaprecision.com/16-9mm-lightweight-stainless-steel-barrel-1-16-twist-1-2x36-introductory-price-on-our-matte-bead-blasted-finish/

When they have them in stock the spinta blem bcg is $110
http://www.spintaprecision.com/blem-9mm-nitride-bolt-carrier-group/

If you are going to have a LRBHO then you will either need a standard carbine length heavy buffer with a spacer to avoid breaking bolt catches or a dedicated 9mm buffer that is already extended for this. There are a bunch of different weights offered from 5.5oz-10oz maybe even more to fit whatever you need. Most will tell you the heavier the better usually but read up on the buffer weights and figure out what works for you.

What Lower do you have, this will help answering a couple of your questions.

You can get the New Frontier Arms BCG, the component version for $149.00.  You can get on of their barrels for for about a $134.00, match grade!  Standards are even a litltle cheaper.  These bolts are cut to work with glock mags also!

New Frontier Armory C 9 Lower...

I use the Spinta BCG. Zero issues.
The NFA is known to break firing pins.

Dave N

+1 for Macon.