I agree with the LFS (local fish store) route. However, they might not have the particular design of aquarium that you want as in the end, it's a piece of furniture as well as an aquarium and some of them are pretty naff. I can't remember where I got mine from but it's a Rena. If you can't find anything you like, consider the custom option. There are a number of custom aquarium manufacturers that will do any size of tank, base and lid you want in a variety of finishes rather than the usual beech/ash finishes that are in the shops. I have bought a number of accessories online over the years from various sites (google is your friend) inc. swelluk etc. but these days, I buy most things from my LFS. For plant stuff though, I go online as I struggle to find a good selection of lighting, ferts etc. in my LFS.