For direct print sales in the U.S. or Canada you can buy through my Aerio store which is run by Ingram which is the source of my print books on all major retailers.
Also, if you are in the U.S. and planning to order 10 or more copies at a time and can wait for the books to print and ship directly (generally allow 30 days from receipt of payment but may be much sooner), contact me (mlhumphreywriter [at] gmail.com) because I can usually offer a 40% discount off of the retail price. With this option you do have to pay shipping costs, though.
For ebook sales, all images below will allow you to buy the book through Payhip using Paypal. If you want to buy more than one title and receive a discount for buying a related title then either go to https://payhip.com/mlhumphrey or click on a linked collection name below instead. Use coupon code HLJFZIIFZW at checkout to get a 10% discount.