Hi Chris,
Some eyepieces barlow well. Some don't. Not many of mine do so I don't use barlows much. The field of view tends to get too restrictive for my taste compared to using an eyepiece of the appropriate focal length. I'm sure this is just due to the combination of eyepieces and barlow that I have. Others love them. You do retain the eye relief of the eyepiece though it can be much more difficult to get your eye in the right spot if the eyepiece doesn't barlow well.
I've got a good Celestron Ultima 2x barlow but in practice only use it for barlowed laser collimation of my dob and to improve image scale on planets with my webcam.
If you get a barlow, get a good one like the Televue, Celestron Ultima, Orion...
If I were in your position and wanted a bit more magnification on planets, I'd get a decent Plossl eyepiece providing about 150x or a bit less. Really wide fields of view are of little use for planetary observing so I'd just go a Plossl. I'd say that 200x would be ambitious on most nights with this scope and as I said 250x is about the limit I'd push it to under good conditions.
The workhorse eyepiece I use on most nights for planetary observing in my C8 (2000mm focal length) is a reasonable 15mm Plossl providing 133x magnification. If I'm really in the mood to spend some time with the planet (and the conditions are reasonable) I'll push it to 200x with a 10mm.
A quality eyepiece can make all the difference when trying to pick out planetary detail in a Newtonian. If you combine a budget eyepiece with a budget barlow the results will probably not be as impressive as getting a decent eyepiece for planetary work.
Barlows are great for boosting the magnification on those rare nights of exceptional seeing though
Have fun,
Doug