$500-$700 price range, which one would you pick?
apples and oranges dude. Give us a bit more background on this choice.
what are you planning on using it for?
plan on competing? if so, what is your prior experience?
what is your anticipated shooting volume?
Chevy vs Porsche.
If the Ruger comes with the glass and what appears to be and aftermarket trigger, it probably best to get it down to around $500 in my opinion. YMMV. Our area is typically saturated in bullseye guns, as it is a pretty big league sport in the northeast.
I think either gun would serve well for bullseye. The bennilli is probably more gun than you need for right now. Getting into a higher grade of gun like that is typically a highly personal decision, and you would probably want to do a bit more research than pick up the first one you find for a good deal. The MkII is the most prevalent model at my local bullseye club by a wide margin.
The ruger can more than hold it's own if you are a newer bullseye shooter. I say to get it down to $500, or less, because around here, another $100-150 or so would put you into used S&W Model 41 territory. For a regular bullseye shooter, a S&W41 is going to be VERY competitive across a wide range of growing skills.
I'm not a bullseye shooter myself, but I spent two nights a week for two years at an indoor range pretty much exclusively devoted to bullseye. Lots of chances to try different setups, and also get some needed constructive criticism from those folks. Ultimately, it wasn't a sport for me, but the experience really developed my skill and understanding.
The Ruger Competition is a good Bullseye starter gun. Jump to a higher end gun when you can shoot master scores with the Ruger.
$550 is alittle high ....probably because of the Leopold pistol scope. Offer $425-450 without the scope that you won't want anyway.