To get into the
juice bottles, you can usually succeed with those thin-tipped plastic pipettes. Bug a friend who works in a research lab

or buy them on eBay, a couple bucks for 10 or 25.
But to refill cartomizers (and juice bottles if you prefer to pipettes) it's handy to have
blunt syringes. (i.e. they do have needles attached, but are not medical-grade sharps. I wouldn't try to acquire/use sharps anyway.)
Heaven-Gifts.com sells blunt syringes for $0.75 a pop (you do have to make it a bigger order to make the savings worth the shipping cost from China), plus cheap empty dropper bottles.
People also use blunt syringes to refill ink cartridges, so you can just find someplace that sells those ink-replacement kits. Again, I usually look on eBay first, just my habit.