Given a $500 budget, I'd opt for a .22 cal. HW95 at $315 and buy a decent scope/mount. This really isn't a "new school" airgun, but an excellent quality gun with a great trigger and enough power in .22 to hunt small game.
+1 My HW95 is .177 but squirrels and house sparrows are my largest quarry.
I would highly recommend the Nikon Pro Staff EFR scope (air rifle approved) for under $150. I've got some other air rifle scopes with mil-dots but the glass isn't in the same league as the nikon.
