There are a lot of things to consider.
There is a need to buy the scales in the first place. They come with displays so you would be up and running in the time it takes to accurately mount the scales.
After that the Arduino solution really is a "how much is the extra functionality worth"? You already have the Arduino boards but you would need to acquire a Blue Tooth Shield plus an Android tablet. Then you get to work out the connectivity from the Arduino to the scales, a reasonable case to put everything in, and all of the other little bits and pieces to make actually 'make it real'. All of this is well covered on his website but reading about what he has done and doing it yourself may have different results.
What might the benefits be? Once you have it all worked out you have a very powerful processor available in the Android tablet. The source code is available so if you are a developer you can very likely get it to do anything you'd like.
On the other hand, how often do you need the extra processing power. For example, to calculate a bolt circle you could perform your calculations elsewhere and then use the original bare bones system with the provided display units to get the job done.
I think it would be more of a "do I want to do this as an Arduino learning exercise" more than a "can I save any money or which is the best financial investment" activity. I am considering it as a "can I make it work with incremental encoders rather than the iGauging scales" simply as a learning experience, not as a "look at how wisely I have invested my time and money" issue.
)Arvid
