I am not interested in sending anything out for work.
Is there any way I can get the tools needed, at a reasonable price, and install choke tubes in my trench guns at home?
I have about 7 barrels to do now, so I think the tools could pay for themselves.

I believe that internal choke tubes need the barrel to be threaded on a lathe. However, of you can find one, a PolyChoke or Cutts Compensator can be silver soldered on the end of a sawn barrel, and both offer adjustable choke.

It's ideal to have a lathe but not necessarily nessary (is that right??). Anyway, if you're really horny to do it yourself, thay can be had for as little as a grand, but they are good for little else than hobby work.  --ST

No, no lathe needed.  Look at Brownells for reamers and choke taps.

The trouble you may run into (don't know what barrels you have) is the internal barrel diameter at the muzzle.  Some barrels are thick-walled, some thin and if it is not already set-up for a choke, then installing one is not as easy as just threading the iinside of the muzzle.  If the it's a think walled barrel, you will need to ream the inside of the barrel down so that the choke tube will be dimensionally flush with the bore.  That's not easy to do and you could easily ruin the barrel if you don't know what you're doing.  

On thin-walled barrels, there may not be enough material to safely thread.  If it's too thin, you run the risk of turning your shotgun into a choke tube launcher.

A lathe is a good idea, but very expensive.  You need a reamer to open up the muzzle end, and the appropriate tap for the thread/style of chokes you intend to use.  If I'm not mistaken, Brownell's has the reamer and taps together as a kit.

What you need is tools with interchangable pilots.  The pilots need to be the specific diameter of the bore; this prevents chatter and helps you keep the tool straight.  

In theory, you could possibly do the work by hand, without a lathe.  If you take your time, pay attention, and go easy you should be able to do it.  If it walks or goes crooked, the barrel is done for.  This is something that I have contemplated for a while, but haven't done yet.  I have thought about this and forcing cone reamers, bore reamers, and the like.

Call Brownell's Technical line and talk with one of their 'smiths.  They might be able to steer you to the right tools and even offer some helpful advice.

I have done 2-3 "by hand" when I worked at a local shop a several years ago. It is very abusive to the tooling because you cannot keep "constant pressure" (ie; your tooling will wear MUCH faster). There are specific ID and OD requirements when choosing what style of tube you will use.

As 2guntom said- Best to call Brownells and talk to a tech.

I saw that "cutts compensater" in a catalog at my old dealers shop, it looked pretty coll, just adds some length to the barrel.