You got lots of great advice about using your grill today, so I won't be redundant.
About an entry level smoker. That's an extremely broad question. I think first you need to decide if you want charcoal, gas or electric. If the thought of checking your charcoal fire, stiring or adding coals every couple/few hours and doting over temperatures doesn't sound like fun to you, you may want electric or propane.
Have never used an electric, can't help there. I never had real good luck with my propane grill, but then again, I never put much effort into learning the "right" way to grill either (before now.)
When my propane grill died, I bought a Brinkman gourmet. It's a bullet style water smoker. It gives good results with minor modifications (about $12.00 in parts and an hour labor.) But it can still be a pain. Every time I think I have it figured out, it goes off and acts like it has a mind of its' own. Still, it's cheap, and I can compensate now that I have some experience.
What type of grill do you have? If I were going to do it over, I would buy a 22 1/2 Weber kettle, and the smokenator smoker for it. I have that set up now, and almost never touch my bullet smoker any more. As a matter of fact, I'm going to buy a propane adapter and turn the brinkman into a propane smoker. I said I'd never use propane again, but I changed my mind.
So, I guess you need to decide if you think smoking will be a hobby to you, or if you just want some good food from time to time. And how much time and effort you want to put into it. There is a corner of smoking meat for everyone, with every level of participation.