This seems a little spendy for video tutorials (peepcode is a good benchmark). Have you considered breaking them up into smaller bits and selling the same $50 content for 5 blocks @ $10 apiece?
This would also obviate some of the risk for the buyer? I.e. if they buy the first one and hate it, they aren't out $50.
(btw, don't get me wrong- $50 is CHEAP if you guys do a good job-- I'm wearing my marketeer hat with this comment)