These works were all commissioned from scratch or customized to meet clients' requirements. The process typically involves a certain amount of research to make the pictures as historically accurate as possible, and it helps if you have at least some documentation - perhaps a diary or other written account, squadron records, or old logbooks in the loft? - and ideally contemporary photographs. I then prepare a rough 'sketch' and a number of drafts to get the composition just how you would like it before making the final piece.
How much does it cost? You will appreciate that it can take probably a week or two, perhaps more, depending on the complexity; so have in mind a budget that allows for that - but in the order of a few hundred pounds not a few thousand. It can be very little for something relatively simple, such as one of my existing pictures with different squadron codes on, if appropriate. And of course it costs nothing just to send an enquiry.
So if you have something in mind, get in touch and I will give you a no-obligation quote and an indication of the likely timescale.