Hi Brian: Wow, you do go for the right price! :-) I guess I did the same when I first started out....by my, how I have changed (smile). Not sure if thats bad or good (smile)
On an 8" saw, I'd do the smaller dado....although I didn't know they made a 6". I take it this is the wobbly dado/single blade...as opposed to the multi blade/knife dado set. $5.95 for a metal dado guard is a good price.
On the 10" you are looking at, other than the bearing play-out, if the table is cast (as opposed to stamped), make sure it is reasonably flat. You can tell by running a 4' level over it. Hopefully, this will be belt driven, an option you will much prefer to direct drive.