do u really need a sight tube.. if the scope came with a sight cap?.. thats what the 8" came with and thats what i've been using.. plus if u went for the bintel u'r secondary would be set anyway.. which i think is the main purpose for the sight tube. But yeah, andrews cheshire is $29.. Also, keep in mind dave that your scope has to go a fair way to u.. and may get bumped around on transit, and maybe the collimation put outta whack, so u'r gonna have to re-collimate it anyway. Which leaves centre spotted primary.. and although the thought of it is daunting.. it really isn't that hard as long as u'r very careful and very patient..
I went for andrews, because it was cheaper.. and the advantages for going for the bintel weren't worth it for me.
also.. andrews don't ship the scope with the series 500's.. or at least they didn't with mine.. they shipped the with the proper GSO plossls... apparently the series 500's are of a lower grade.
the full instruction manual looks good though..
el