I agree with the mod crowd. My suggestions for a KILLER (no pun intended) set up under $100 are as follows:
ecigworkshop.com for stunningly gorgeous custom made wooden mods that take PROTECTED 18350 or 18650 batteries. Simple and elegent with a silent electric horn switch. Expertly wired and threaded for any 510 carto,atty or tank.
If your not into wood.....I recommend the NEW version of the Telescope. You can get them at GotVapes.com Another simple,elegant totally mechanical (read SAFE) mod that can be adjusted for different size batteries
For leakproof, foolproof pyrex tanks that take a standard (read CHEAP) SMOK or SmokTek cartomizer... theecig.com
Juice...meh...who the hell knows? It's so subjective and you didn't mention what flavors you like. Some companies are better at the dessert and sweet stuff then they are at tobacco and other companies specialize in tobacco and menthol with just a few specialty flavors. I personally use HALO, not only because I love the flavor but I trust the purity. Unfortunatley they are very pricey.
One more suggestion.....I know your looking for good value...but there is one thing you should not try to save money on if you go with a mod...the charger. Get a GOOD brand name charger. It may seem like a lot of money...but it's worth it.
oh...I meant to add.....if part of the reason your looking at the 510 is that you want something more "realistic"......and you don't forsee getting into mods at a later date...I recommend the KR808. The XL 102mm battery stays charged at least 6-8 hours and a good quality one is a workhorse. Bloog has a very nice product and right now they have a 4pack deal on auto batteries for 19.95. You simply can't beat that. I have not bought from them in a while but in the past I have been extremely pleased with their products. They also have manual batteries.