Do not get your multi engine cimmercial yet. Get your cfi and ii and teach. Whst you dont know is thst you are going to need at least 25 hiurs in mske and model to be able to teach in thebplace you are going to work.
Once yiu get employed that elcheapo multi add on will cost you more than this method becausr you will need to buy 10-15 more hours in the plane.
Also we have a garmin 430 equipped be76 thst goes for $255/hr dual in seattle area .