The price the supplier Dusty used is not too bad. £9.99 for a Gen 1 Fazer key. Depending on their packaging, first class signed for is £1.75 for a small letter, £2.08 for a large letter so basically it's £8.00 for the key.
Cutting from a photo is simple enough if the trader has the required software & hardware. Also, knowing which vehicle the key is for is a head start.
Of course, a key can even be made by hand!
This leads to being aware that leaving (any of) your keys on the bar, shop counter, etc. unattended or unwatched is a real no-no these days as a thief only needs a decent photo of your key to make their own & help themselves to your bike, house contents, whatever!
There is evan a mobile phone app. which will scale the key for you.
Caution is also advisable when using any postal method as the there party by default will know where your house & bike, etc. are located!
As a price guide...Part of my business is key cutting (though I only cut from your key). My Fazer 1 keys are £4.00. Places like Timpsons are about £7.00-£8.00.
Yamaha barrels are renowned for being fiddly as they are on top of the yolk so prone to moisture ingress. I spray GT-85 into mine regularly which helps a lot!