You need to tell us what your definition of fun is.
Some guys love shooting big bore revolvers but I can't stand it. Some guys think .22's are boring, but I'm happiest when punching small (by my low standards, anyways) groups at 25m with my Pardini.
My suggestion for a starter with no experience is always as follows:
Option 1- Buy a used .22 and a mountain of ammo. More shooting more often is more fun. I've found the gun matters far less than shooting friends/fellow competitors in determining fun. Something like a Buckmark, Ruger Mk4, or S&W Victory would fit the bill well and be no more than $500. A bit pricier but very nice is the S&W 41.
Option 2- If you're set on centrefire buy a used 9mm and a smaller mountain of ammo. Same logic as the above but with a bit less trigger time and a little more pop. If you're interested in quickly moving into IPSC, IDPA, etc this is likely the smart move. Glock and S&W M&P are the obvious choices here as they're a dime a dozen and well supported. If you want a metal frame you can't go wrong with the CZ75 family.
Option 3- Be different, buy a revolver. Cost of ammo becomes a large consideration here, as factory .38spl or .357mag are substantially more expensive than 9mm. If you already load for rifles buy a set of dies and it's a wash. I'm partial to the S&W 14, but it's .38spl only.
Good luck.
Oh ya, forgot one last thing, a Browning Hi-Power is never a poor choice.