Hi there, I hope you're doing well.
I'm writing in response to your ad seeking a graphic designer to create a logo and a banner for your YouTube Channel.
Being a graphic designer I'm interested in this project.
I've seen the images that you've attached as the existing logo and banner of your channel.
I've got an idea in my mind for what are you looking exactly.
Moreover, I've been designing professional banners and logos for YouTubers.
I can work for you in just 600.
If you're interested in working with me, I can show you samples of my previous work as a graphic designer.
I hope that I'll get a chance to work for you.
Waiting for your positive response. :)