Try to find plants that grow well in YOUR setup, rather than changing setups. Get something that is a good intermediate grower. Then push the limits a little, something that rows well on the upper or lower edge of intermediate. Later on you can focus on a lowland or highland setup. Getting a good collection in this hobby requires (i) money, (ii) time, or (iii) connections. So if you don't know someone who's willing to give you cuttings or divisions for cheap or free, and you can't afford to buy the expensive stuff, use time as your weapon. Be on the hunt for people that are willing to give out great plants at low prices. Facebook, reddit, and ebay, follow carnivero and florae and follow their drops. Find small, young plants and grow them to be amazing mid plants. Then trade up (or sell).
A good example: Carnivero's Veitchii CAR-001 (
https://www.carnivero.com/products/nepe ... 7941328939) is normally $100 for a medium plant through Carnivero's website. A few drops back, you could have picked up one of their XS plants for $40 (normally $65). Grow it for a year or two, and you have a medium plant. Grow it for a little longer, you have a big plant. That same $40 plant becomes worth $500-1,000+ (
https://www.ebay.com/itm/224845127449?h ... SwmsNiD-OL). Sell it at that point, and you can buy 12-30 small plants and repeat.
If you have the time to find the deals, and have the time to grow the plants, and have the green thumb to get it done, you can do wonders. Sounds like you have all three.