It's pretty expensive. They give you 100 free credits but I burned though that in about 10 minutes just trying to figure out how things worked. Didn't get any nice images.
After that, it's $1 per 100 credits, so about $6 an hour maybe.
One credit is one regular-sized picture generation. If you want to make it bigger or run more steps (in my experience, this is less useful than it would seem), then it can run up to 3 or more credits per generation. That's still 3 cents a picture. Compared to Dall-E and even Midjourney, that's crazy cheap.
After that, it's $1 per 100 credits, so about $6 an hour maybe.