Just a suggestion. Since you don't have to worry about it blooming until spring, you can always pick up another azalea of any variety to fill the space and then swap them out next year when the one you need is more likely to be available. The shipping costs for the mail order places always were pretty shocking to me and likely more expensive than a generic small azalea at a big box store. If it's one of the small red azaleas from Lowe's or HD (and don't have my luck), then I can almost guarantee you that you'll find it again next year. Not sure what variety you have, but Hinos and Hershey Reds are pretty easy to find in the spring.

Our Lowes still has some in stock. Check your Lowes and local nurseries. They stock until Fall usually.

Do you have any local nurseries? I went looking for some plants this weekend and all my local places had a ton of azaleas (some looked better than others, summer can be pretty iffy in terms of quality). I actually walked out with 3 Bollywood azaleas when I had gone in for weigelas lol.

I also went to a nursery this past weekend and they had a entire section devoted to azaleas.

The nursery I used to work at got an initial shipment in the spring and then pared back their selection as the summer went on. You should still be able to find azaleas relatively easy though.