I'm in full agreement with RBernie. I've never regretted "missing out" on a gun that I passed on, when I had the time to get home peruse the 'net, and pose a "should I buy it?" question. If I didn't turn around in the traffic for that toy, it didn't bite me good enough to make me green with envy.
remember DeNiro in 'Ronin': "whenever there's any doubt, there is no doubt".
I'll have to amend that--if you can sell it for 95-97% of what your total costs will be, then I'd do it, if it's a question of curiousity. At least that way, your "rental costs" will only be ~5%. If it's a gun whose configuration and ergonomics you're familiar with, and you still pose these questions, I'd pass outright.