We just installed a new kitchen in the summer. The budget and timescales were very very tight and we tried to do a lot ourselves .
We bought Ikea units, built them ourselves and had them fitted by a joiner. Bought a deeper worktop from another supplier as Ikea units have no void at the back for services .
Bought appliances elsewhere ( cheaper or better quality ) . Ditto taps and sink.
I spent ages researching each appliance, reading reviews, researching prices and then using price match to get most of them from the same supplier .
I also had to watch as we are in a flat and some companies will only delieve to the kerbside ie out in the street .
This research got my appliance budget down from just over £2k to 1100 so well worth it ( also better quality ).
But I had the time and and knowledge to manage the project myself, which saves a lot of money . And I wanted to chose my own things from a range of suppliers, not just from one company .
I accept that not everyone can be bothered with this. It’s a lot of work and probably takes longer .
I agree the best thing is to get a joiner booked first, as the best ones will be booked up months ahead. Usually they have their own plumber, electrician and tiler that they like to use.