+1 ^ @mredge73
Definitely use MFL connectors, easy to disassemble for cleaning. Consider using (correctly sized) Oetiker clamps instead of regular worm gear hose clamps to clamp the line onto the swivel nut barbs permanently. A pair of pinching pliers will work fine to "crimp" the ear, no expensive tool required.
I would consider using BevSeal Ultra "glass" barrier line for your beer. The John Guest "push-fit" fittings are the best/easiest as it is very difficult to slide that line over a barb without damaging it, but it is possible by heating in boiling water and swaging. Those fittings
are designed for semi-rigid line, you
cannot use them with the regular soft Vinyl/PVC lines like Bevlex 200.
If you are going with BevSeal Ultra, count on using 16-24' per tap, since their resistance is very low (they're slick) and they're actually wider, at 0.20" ID, not 0.1875 (3/16). BevSeal Ultra is totally taste free, even after beer has been sitting in there for 2 weeks or longer.
I use 1/4" Bevlex 200 line for gas. They are transparent, so I can see if any beer got in, which sometimes happens. 3/16" or 5/16" work just as well, the diameter is not critical for gas.
Also check out
RiteBrew and
Birdman Brewing. There are others.
You can find reconditioned "real ball lock" kegs for $40-50 looking for the right offer.
Adventures in Homebrewing and other vendors often have them on sale in 4 packs. I'd stay away from converted pin locks (sometimes advertised as
low profile), less will fit in your keezer/kegerator since they're wider. Learn about both kinds to know their differences and how to spot which is which from 10' distance.
Even brand new ones can be had for $75. They're made in China, but have favorable reviews. You need at least 2, but 4 or more is better.