If you use 3mg e liquid you'll want something stronger for nic base. 100mg will get the most out of your money as you'll only need a little over 1ml to make a 30ml bottle of 3mg e liquid. If you don't feel comfortable working with 100mg you could try something like 48mg, but we long as you aren't planning on getting the nic base all over yourself you'll be fine with 100mg. If you try one of the e liquid calculators you can get an idea on how much nic base you need to use with the varying strengths.

If you buy straight up 3mg you won't be able to make juice with a higher nic content, you're locked in at 3

Vaporstek , great stuff.

Buy 100 mg nicotine and vg and pg seperately, and put 0.93 grams or 0.93 milliliters per 30 ml of e-liquid to achieve 3mg overall nicotine level. A small 100mg nicotine bottle will be enough for liters of juice.

I use nicotineriver, just plan on spending 50+ to get free shipping and it's well worth it. 35 bucks for 500ml of 100mg and throw in some flavors to hit the 50 dollar mark. You can also go for the 1 liter 100mg for 60 bucks. I have no issues with their nic, I don't see myself switching brands anytime soon unless they decide to again change their shipping policies. If you don't take advantage of the 50+ free shipping then it's not worth it though because their shipping fees are ridiculous if you plan on spending below 50 bucks.

If you don't want to mess around with high strength nicotine, you can get flavorless 3mg eLiquid here

Or get the 100mg here, if you're comfortable with that.

I prefer to buy 100mg nic and mix down to the level I want my final mix at. You end up paying more for the same amount of nicotine but it's "concentrated" and goes A LOT further.

Whatever/wherever you decide to buy from make sure it's not Nude Nicotine. It just took me over two weeks to get an order in from them with no shipping notification.....at this point the best Nicotine I've ever used has came from Carolina Xtract, but they are a bit on the high side - but shipping is fast, quality is great, so is the packaging.

One more thing to keep in mind with 100mg nic, is proper storage. If you don't store your nic base in the fridge or freezer and divide it up, 100mg will oxidise faster than 24 or 48 mg.

ignore what your friend says. vape at the strength you want.
buying 100mg nic is for adding to juice that has none in it or DIY.