I think most dont charge, I started a thread on here and had some good info but prices have changed quite a bit this last week or so.
The monj website has maintenance provider info.
From what I can gather Pharmulus, Swift and Lotus are all good with no monthly fees.
I have just ordered from Lotus, I will email them go clarify but from what I can gather you can go up to 8 weeks and stay at same dose, or 6 months if over 20 BM8 but likely to go back to 2.5 unless you can prove stock pile. I wont mind going back to 2.5 for maintenance as hoping to have around 1.25 for. maintenance.
I have 4 x 5mg pens in stock now and had planned to buy 1 more. Which I will probably do from another maintenance provider (likely Pharmulus).
Both Pharmulus and Lotus are around £170 as their regular price which is significantly less than most but I want to be able to guarantee to buy a pen with a BMI of 21/22 so I am going to email them both to discuss. Lotus have a good regular customer discount, you get points for spending with them plus discount for buying 2 pens (but obv no good if you want to buy less regularly).
Its a bit of a minefield!
Oushk are £15 a month I believe but you can just order whenever, I am sure there are prescribing limitations as presumably cant be on high dose and go back to it after say 18 months, they were also higher price for pens.