Hi Paul,
When you say that you willl change "host", do you mean web hosting provider, domain name or ecommerce platform? If you meant :
Hosting provider : you shouldn't have to do any 301 redirect as all the Urls will remain the same, only the IP adress of the website will change, but this is not a big deal.
Domain name : If you have a apache server, you could create a .htaccess with single line of code that will redirect any pages or images on the old domain to the new one, without having to create a single 301 for every file.
Ecommerce platform : This one is the hardest one. If you are to switch to a new ecommerce platform, I suggest you try to keep as much as possible the same Url structure as you had if possible as it already looks good.
Depending on the type of move you do, please specify the kind of change you will be doing so we can help you better.
Best regards,
Guillaume Voyer.