Hello Bob,
You asked a good question, but you are not going to like the answer.
Good and cheap does not walk hand in hand.

The reason why the established companies are head and shoulders above the generic equivelent is because the established companies has a much higher quality standard.

LMR 400 is a two edge sword.
Yes it is good, but it is also slightly more cost and a lot less durable then other types of cable.

The main use for LMR 400 is the higher ranges of UHF due to the fact that it has a lower loss rate.

A few things to remember, its center conductor is 10 gauge / not 12.
Its shield is foil - braid, not copper conductor. Its dielectric is foam not poly.

You have to buy special connectors, you aren't going to screw a PL connector on it and you can't solder it.
You have to have crimp pliers - and the $2.50 or more PL connectors to use it.

The foam dielectric is hygroscopic - it attracts water and it's life span is maybe 10 years. You aren't going to put it up and walk away and 30 years later still be using it - because once the water gets inside of it, it is ruined.

The outer jacket is very fragile, if it gets a knick or gets damaged, you are going to have to either splice it or replace it.

If your work involves UHF - your needs would be better off met with Hardline then with LMR 400. There are radio towers out there with hardline that is 40 years old that is still in service.

Often times, if you know the right person, they will sell you used hardline for a lot less money then new LMR 400.. After all, unless they are going to build a repeater - they probably don't have any use for it.

I hope this is not information over load.

When using generic LMR 400 - you want to make sure to have it sweep tested before you put it up. The Chinese aren't real particular what they sell, and most times the deal is that there is a bad spot somewhere in the coax and that is the reason why they wholesale it with no name on it.