resume flying after 25 year layoff

IFR simulation (most cost effective) at home training before beginning
actual flight training. Any advice would be appreciated to help me develop
a cost effective way to re-learn to fly.

Re IFR simulation, you might want to take a look at ASA's IP Trainer. I
have kind of a love/hate relationship with it as the concept is
absolutely outstanding but it may be the buggiest released software I
have ever encountered. I just finished helping with the beta test for
7.0 and found it improved but still buggy.

The concept is to present an extensive series of lessons from the basics
to advanced, monitoring the student's performance and giving very
precise feedback. Audio and scrolling text feedback during plus
"evaluation" after the exercise. On the simple altitude/heading hold
you will get little diagrams showing your maximum altitude deviation,
maximum heading deviation, etc. for each phase of the exercise. On more
advanced lessons you might get 4 or more parameters measured times 5 or
6 phases of the "flight." If you screw up badly, it stops you and you
can back up at bit and try again. If you fly to specified standards,
you "pass" the lesson.

Major bugs still in the beta include the way they handle the panel timer
-- the monitoring software often does not detect that you start it, then
stops you with a "timer not started" error even as you watch the timer
run happily on the panel. Another beauty is that when you stop and go
back because of an error, the software sometimes gives the trim a good
whirl -- when you restart what was a trimmed airplane you are instantly
in a dive.

But compared to just wandering around using a free flight simulator,
this is much better for training. As a computer designer and programmer
by trade, my bug tolerance might be lower than most, too. (It must be,
as Jackie at ASA seems sort of politely bemused by my feedback.) So YMMV.