Hi,
First - Certification.
If the electrician installed a new circuit, then he needed to issue an Electrical Installation Certificate. If he altered an existing circuit, he needed to issue a Minor Works Certificate. Certification is NOT OPTIONAL for work that was carried out in your kitchen and it certainly isn't chargeable.
Second - Local Building Control (LBC) notification
Any work in a kitchen, unless replacing like for like, carries a LEGAL obligation for the installer to notify LBC. When you try to sell, the searches take into account LBC notifications. This is when you could get into trouble as the "new" kitchen isn't on the list and may put buyers off. You may get reported and may have to prove that you did not do the work yourself, as if you did the maximum fine is £5,000
NICEIC have a number of schemes, he may not be on the Part P scheme, and may not have been during the installation. If he was on the scheme at the time then it would have cost him pennies to notify to LBC post project.
Write to the electrician and tell him that you intend to write to the NICEIC as to why you did not receive a certificate from their member and why you were told that providing one was expensive. Demand an explanation from him in 7 days.
If you get the silent treatment, which is typical when you have been caught, write to the NICEIC and demand answer to the same questions within 14 days.
When you get nowhere with them, as is typical, report the electrician to local trading standards for his illegal practices and get in touch with LBC to confirm that work was done, you have reported the illegal work to trading standards, and listen to their advice as to what to do next.