If customs stop a parcel from outside the EU that contains any nicotine, it will be seized and destroyed unless that partciluar product from that brand is certified TPD compliant AND the bottle is under 10ml. If the bottle is nicotine free and that product is certified TPD compliant, you can import it, but you will have to pay VAT, and if your goods are worth €150 or more, you'll have to pay import duties as well (payable not only on the value of the goods, but also on the VAT and all shipping charges). This means your 120ml 3mg would be seized, but a 0mg equivalent might not, depending.
Many US vendors no longer ship to the EU as it is not worth the hassle for them. For those that to, it can be worth trying if you accept the seizure risk. Very few shipping forwarding companies will handle vape-related stuff, or liquids at all for that matter, but again you may feel it is worth the risk (bear in mind that they'll look for payment invoices when presenting the parcel to customs, so even if they accept it, you're opening yourself up there).
If you ship from Germany, or any other EU country, you will not have to pay anything to import it (just the sales tax when you buy, which may be a different rate to that in NL). If you ship from the UK, you will have to pay VAT, and if the goods are worth €150 or over, import duties (again, payable on the goods + VAT + shipping).
Best bet is to buy longfills and nicotine shots within the EU, or mix your own from concentrates. Last I understood, the US has already introduced stringent regulations on shipping of vape liquid, so for shops that do not have a strong Brick & Mortar presence, things are already collapsing there.
