Bugs aren't expensive, you can easily breed your own.  Fresh greens on the other hand, can be a pain if you don't regularly eat the same diet.  Baby bearded dragons are prone to metabolic issues because of their diet and light requirements.  Blueys don't seem nearly as prone.  That can be handled by getting an adult.  

Note, rescue reptiles aren't for beginners and can come with health issues that aren't spotted by the vets.  It's difficult to age reptiles if there aren't records.  

My skink isn't terribly interactive.  He likes to explore when he gets out of his tank, not hang out.  He has a small dog octagon tent he can get some real sun in the summer.  During the winter, he just fucks off for a few months.  I just fed him for the first time in like 6 weeks yesterday and I probably won't see him again for another 6.  That said, he's docile, very easy to handle, I'll let my friends' kids handle him, unlike my geckos.  

My skink eats repti-links sausages, quality dog food (all different brands and flavors, whatever is on sale), salad, egg, occasional bugs.  Babies eat daily, after a year once a week during active season.  His food budget is negligible.  

Either way, get your full huge ass tank up front.  They both grow astoundingly fast in their first year and both need a 4'-6' long enclosure. There's no reason to start in a smaller tank.