With regard to your cheapo refractor, in some cases anything's better than nothing at all, unless you're looking at terrestrial (landbased) targets, don't worry about the erecting lens. The barlow, if useable at all, will only be useful when the atmospheric conditions are suitable. i.e. no jetstream, (see
http://squall.sfsu.edu/crws/jetstream.html) clear skies and no wind. Even with modest magnification (say 25x or greater) you should be able to make out Jupiters disk and 4 of the moons and see saturn complete with rings. The moon is also a great target at almost any time of the month.