ADA tanks are not cheap, the small 2.5g tank is $60 and the 18g starphire one is $280. However, the craftmanship is excellent, much better than anything else out there.
The nanocube tank systems with the curved front, filtration hidden in back, and lighted hood system makes great planted tanks. There are three brands with similar design; JBJ Nanocube, Current Aquapod, and Oceanic Biocube. They're within the range of $120-140.