The coffee is the most important bit. Bear in mind that when you start out grinding etc you'll find that you'll chew through beans until you have the grinder at the right setting and things start to gel and espresso comes out.
JBM is expensive. So it may be worth starting off with something like:
1) Tinned beans from the supermarket - to get the grinder at a point where you get something out! This will stop you wasting your good beans.
2) Beans in the £3-4 category initially. I guarantee that you'll be fiddling with the settings, trying different things so you'll burn through a bag quickly.
The next bag will zip by as your friends/family try 'real coffee'...
Note that different beans may require some fiddling of grinder/brewing settings..
Suggestions, for middle of the road non-acidic beans:
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Australian Skyberry which is quite bombastic. Has a hedonistic smell and flavour intensity to match. Good flavour just expect it to be BOOOM in your face. Smooth but intense.
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Iapar 59 The bean in the videos. It's very unassuming and is, well, a complete opposite to the Skyberry. It has smooth chocolate, sweetish and nutty.
However there are blends you could look at. They'll taste very different to single origin beans such as those above. Lastly remember that the beans that someone likes may not be the bean that makes you think mmmmm... that's nice. Everyone is different. However what it does do is give you a reference to which you can say I like this but that's was a little too soft tasting etc.
Remember that beans may take upto four days to 'degas' after their roast date. This is when the Carbon Dioxide from the roasting is still escaping from the bean. I will affect the flavour slightly. So be prepared to put the beans to one side and try them again late if you think that they need more time.
Other bits - just as Raymond has said.
Tamper is basically a metal disc with a handle. For me it's the feeling that I'm not about to break it when using it. It should fit your portafilter basket snugly.
The jug - mine's a Motto 0.75 litre jug. You'll need some space in the jug as it'ls only half filled with milk, the rest is taken up by expansion of the milk foam. I've managed to expand the foam to about an inch of the top of the jug. So choose a size that fits your normal cappuccino/latte size accordingly.
A narrow spout allows for latte art later but focus on getting good taste before that!
I've got to the point where I can tell with my hands and the noise of the steaming when to switch from adding air to stretching to finishing. However a thermometer is a reliable and very useful tool when you learn.
So...
1. The beans/coffee is the most important - that's where the taste comes from.
2. Next important is the grinder as that unlocks the taste from the bean
3. Lastly coffee machine as that washes the taste from the bean into the cup.