Your stated desires make it increasingly difficult to offer recommendations, lol. There just aren't many colorful, exotic looking snakes that reach the size you want.
blue beauty snakes (internet image)
red tailed green rat snakes have the color and size you want - but they (like ETBs and GTPs) have highly specialized care requirements. You said that you don't mind that; but not a lot of people have long term success with them.
carpets I've already suggested - but keep in mind that there are other colors/patterns than the ones I posted
bloods - I'll add a shot of one of my old reds (I prefer the look over Borneo's, personally)
They won't get the length you want; but they're big snakes for their size.
You could also consider Timor pythons; but there's a major commitment in terms of caging as they require roomy caging as juvies and adults.
If you want cool/exotic, Boelen's pythons become available for a brief period each summer. I don't know that the prices are down to your desired range yet, but they could be (I haven't looked at them in a few years)