High handicapper club advice - full custom fitting vs static fitting?

I am a high handicapper (26), and I am looking to purchase a set of clubs to upgrade from my starter set.

I am considering getting a new set of irons fully custom fitted, or else getting a static fit for shaft flex etc and buying a suitable 2nd hand set.

Can anyone recommend which one to go for? i.e. would the full custom fitting be worth it?

I am considering the 2nd hand option as it would save me quite a bit of money. i.e. spending roughly £250 rather than 500+