Hi, welcome! Have you considered plant growth above the water in a paludarium style? You could grow local native plants that are happy with the heat. The roots are a pretty awesome addition to the aquascape too! Bit of a strange suggestion but Charlie moorcroft keeps tropical fish outdoors in ponds, as he is based in florida - might be
some inspiration there. You could also check out south African biotope aquariums for inspiration.
The benefit of using local plants is that you can get them for cheap, or for free. Just make sure you know what you are collecting, and that you are not taking too much.
I also got a secondhand set up on Facebook marketplace in the UK. Maybe eBay might be better for you? Or you can look for any other aquarium people local to you (I did this through facebook) and see if anyone has any spare kit for sale.
I am currently doing my first low budget aquascape and I have managed to keep costs low by:
- repurposing houseplants for growth above the water
- getting my tank, lights and heater secondhand
- DIYing elements like the mattenfilter and backdrop to cut costs
- using cheap play sand for substrate without adding aquasoil (plants will grow slower but that means less maintenance for me)
- collecting local native moss rather than buying it
- swapping/begging for plant cuttings haha
- buying my tank and kit secondhand
- keeping the setup as low tech as possible . This means using my dechlorinated tap water without adding things to change water chemistry, and I'm not adding cO2. Using my own water does mean I can't keep some of the species I originally wanted to, because the water is too soft for shrimps and snails. But I'd rather work with the water chemistry and make sure the species I can keep will thrive. And there's less chance of things going wrong!
Hope some of that is helpful.
Good luck