@Skifflexie: since i have been following this thread from the beginning, allow me to chime in. with ~$300 at your disposal, i would get 40-55gal of tank for around $150 just like how i was suggesting earlier in the thread. There's no shame of coming from a low income family or how inproperly we've been keeping the fish due to the lack of knowledge, just make sure you take care of the fish when you got the chance, very much so like how you take care of the reptiles you said to have. We're in the same shoes when it comes to how our rooms are furnished, just barely anything. I think by getting a bigger fish tank, it can really take your mind off when you're stressed out or simply sit back and relax a bit. Therefore it's a good investment i would feel good about even on tight budget. Right now, i would focus on getting the fish tank you that you think is a good deal and slowly move the fish you have in the 15gal to the bigger tank. As for others who have been giving advices not related to the original intention of the thread, they're just doing you and the fish a favor, therefore please don't feel offended. Good luck with school too
ps: i have a laptop, a desk, a fish tank, and a bed in my room