Posting a question without having done any research is not unusual (consulting pprune is a start, is it not?), but writing a reply without having anything to say is a different matter (although not too unusual either...). No offense.
M.85, getting an instructor rating is generally not a bad idea. When I did my AFI course in the late 90s, I paid about GBP4000 (if memory serves), which wasn't the cheapest back then. But then again, you might not want the cheapest, since there is much more to consider than price. How many aircraft and instructors, what state are they in, how fast will they get you through the syllabus (mine took just over two weeks), will they get you in touch with someone who recently did the training with them, would they possibly offer you a job with them afterwards, will they have an examiner booked for you when you are ready, reputation of the flying school? At this point I can highly recommend T.G.Aviation in Manston/Ramsgate, they scored 100% in everything I mentioned (didn't offer me a job, but then again, I didn't ask). The day I did my test I had three job offers from flying schools as an instructor, and I am sure that the right choice of training facility did have something to do with it.
Back then there was no shortage of instructors though, which did reflect in the salary you could expect. 200 pounds retainer per month and 10pounds per flying hour was not unusual, but I don't know what the situation is at the moment. Since it is not possible to go down the 'self-improver'- route any more, I would have thought that there are far less instructors around. All the wannabes do the approved courses now, and most of them are expecting jet jobs at the end of their training, possibly settling for a modern turboprop with a pax airline. They don't even seem to consider an instructors job or air taxi etc. any more to get experience (that's my personal experience with the 'new' chaps). But, as I said - I don't know what the instructor job-market is like right now. The rating itself is very good, though. I learned more about (my) flying than during the time to get my fATPL. And it's heaps of fun, too.
But is the instructor job really the one for you (as FlyingForFun already mentioned)? I disagree with you that there are no jobs to be had at the moment, especially for more experienced people. The airline I work for has both lost and taken on new pilots, and that is pretty much true for a lot of the airlines, at least in the turboprop world.
Good luck, and happy flying.
des