First thing I would do @lene is do a Google search for that mod you have your eye on, pound to a penny you'll find it cheaper and perhaps within your budget.
Funny that coz a vape shop opened on my street and they had same kind if stuff in. I thought it was strange to stock such high end gear when the market for them must be quite small.
Personally when I'm buying anything that can be lost,easily stolen or more likely to be damaged then I keep it to a point where if it happened I'm not bothered too much about the cost of replacing it.
I thought DNA mods were quite dear until I tripped over Dicodes... saying that Purge mechs are eyewateringly expensive as well. Still, cheaper than a 30 a day habit.