Even better, go to Themeforest.com, they have a section for html emails. there's comments and amount of purchases so you can make up your mind.
I've bought this one.
, I believe it came with instructions to upload the file to mailchimp once you make changes to it.
I'm not very knowledgeable on HTML Emails but these templates are cool because I could open them in dreamweaver and change the content and images in Photoshop and then upload.
Or just upload the template to Mailchimp and make the changes in there.
Keep in mind that with these paid templates you're paying for the compatibility, they test them in current versions of major browsers, email providers I believe.