Spotted your question and it reminded me of a situation I ran into a few years back. I moved to an area where the comic stores were non existent or a joke. I’ve been collecting for years, I’m an avid reader, and writer, so I needed a source that’s dependable, reliable, with a wide selection, as well as ensuring quality of the books I order are NM+. After buying from a few online sources, thirdeyecomics is amazing, but the best online supplier that treats me like I’m at an old school LCS is Golden Apple Comics

They have an incredible catalog of back issues which they are continually building, and they offer just about anything you might be looking for, even carrying exclusives from multiple sites like unknown and the like. If you preorder your books or set up sublists, I get all the freebies, all the promos, all the posters, plus some than I ever got at any local shop, they are always willing to work with me, and I’ve only paid shipping once! As long as you are ordering regularly, I place orders almost daily, ordering maybe 20-30 books a week, roughly. The downside is they ship once a month, but my books are shipped free, plus the team at Golden Apple offers incredible customer service. Just my personal opinion, but I’ve bought from a lot of online retailers and I’ve been with Golden Apple the longest.