Clinics offer what private arrangements cannot: screening, expertise, and a legal position that has been tested. In exchange they cost money and impose process.
The common routes
IUI places prepared sperm directly into the uterus around ovulation. Least invasive, lowest cost per cycle, lower success rate per attempt — usually the starting point where there is no known fertility problem.
IVF fertilises eggs outside the body and transfers an embryo. More invasive, more expensive, higher success per cycle. Usually where IUI has not worked or where there is a reason to start here.
ICSI injects a single sperm into an egg, used where sperm quality is the limiting factor.
What clinics require
Expect screening of both intended parents, counselling in some countries, documented consent, and — depending on the country — rules about who is eligible for treatment. Waiting lists are real and can run to months.
Using a known donor at a clinic
Often possible, and it combines much of what people want: a donor the child can know, with clinical screening and a clearer legal position. It requires the donor to attend, be screened, and consent formally. Ask early, because clinic policies differ.
Cost
Varies widely by country and by what is reimbursed. Reimbursement rules in the Netherlands, Belgium and Germany differ substantially, including on the basis of relationship status — a question worth asking your clinic directly and early.