Unfortunately I don't have the full details any more of what I paid when I did my part 61 IR, but from what I can remember the costs are similar to the ones I listed in the other question you mentioned:
- Aircraft rental
- Instructor time (air and ground)
- Materials (books, DVDs, charts, hood, timer etc.)
- Written test fee
- Examiner's fee for the actual test
If we assume a part 61 instructor (\$40/hr) and an IFR-capable rented aircraft (\$130/hr wet) then we come out with something like this (you need a minimum of 40 hours instrument time):
- 45 flying hours with instructor: \$7650
- 15 hours ground school (instruction and simulator time): \$600
- Materials: \$600
- Written test fee: \$150
- DPE test fee: \$400 (plus \$130 rental for the aircraft)
- Total: \$9530
Note that under part 61 you also need to have 50 hours cross-country PIC time, which I didn't include in this calculation. And I increased the materials cost slightly here, because IR materials seem to be more expensive than private pilot ones.
Key factors to consider are the instructor (as with any training) and the aircraft. A good instructor will help make sure things stick in your mind, even if the training is accelerated. I required 49.6 dual hours for my IR according to my logbook, but that was spread out over 10 months and I could certainly have reduced it by flying more often.
As for the aircraft, it's important to think about which aircraft you'll use your IR in, because training on a glass panel will probably be \$20+/hr more expensive than on 'steam gauges'.
Finally, you can make a lot of use of PC simulators like Microsoft Flight Simulator to practice instrument flight at home, which will be a lot cheaper than doing it in the air and it's surprisingly effective. Your FBO or flight school might have something more advanced, of course. And self-study in general will cut down on the ground school time you need.
I have no experience of part 141 or accelerated courses, so I can't say anything useful about those options but I would certainly research them if I was considering an IR. "Worthy" is a fairly subjective thing, but you can always ask around for recommendations, speak to previous students and so on.