You know, I have to wonder, just how important is the 3.5 " shell ? I would look into the value of a 3" vs a 3.5" more. On a lark i just googled "3.5 inch shotgun" and the first thing that caught my eye was this:
http://www.fieldandstream.com/articl...ut-shogun-ammo
then this:
http://www.24hourcampfire.com/ubbthr...h_more_range_d (8 page thread )
Maybe you've already hashed this out for yourself, I dunno, but a cursory look has me wondering about the practical value of a 3.5" shell. I can't say for sure, but I think your options on available shotguns open up a bit more with a 3" shell. In any event, if i were in the market for another shotgun, i'd be looking very closely at the pro's and cons on the two shell sizes.
As autoloaders go, i'm not sure there is such a thing as an affordable autoloader. Personally If I had 800 to 2,000 to blow, it wouldn't be on a scattergun.