Definitely not a rip off, great setup, I think you're exactly right about a new case and gpu, though the gpu is plenty capable depending on the workload. For a case, I recommend the "be quiet! Dark Base 700" this case looks great and has an upgrade path up to professional style setups ie. threadrippers and high end xeon builds. For something a little bit lower spec, Ive sold a few "Phanteks P300 or P400s", they cost a fair bit less and are amazing cases to work with, I remember building my first pc where the case wasn't super low end and the switch to the mid range Phanteks P300 was like night and day. It really depends on your budget, but those are two great options for two budgets, (High and Mid).
On the GPU side of things, do you have a specific workload, do you need cuda cores from nvidia to render graphics in an optimized workload, or is gaming a priority. There are so many reasons to upgrade, and many more not too.