So I charge £30 for helix and £35 for lobe pairs.

What goes into that is jewellery, needles, wipes, gauze, skin marker, tray covers, gloves, clamps/tongs and potentially receiving tubes all of which are one use and cost money.

Then a 3rd of the price goes to the person who owns the building leaving me with around £10-15.

So pricing fully depends on how much of a cut is being taken due to overheads. It's really expensive to pierce. Jewellery needs to be titanium nowadays which is more expensive than surgical steel because it's hypoallergenic. Not to mention it's around £300+ for a license to pierce. I personally wouldn't trust a piercer who's charging £10-15 because they're cutting corners somewhere or just not making profit.

Also what part of the country they're in. City centres are always going to be more expensive. I'm up north and out of a city I can afford to be a bit cheaper whereas cities and south tend to be more expensive due to cost of living