I’m a scrounger too. I have yet to purchase an aquarium for the fish room. All have been CL scores 100g and 220g, side of the road 90g, or gifted for various reasons. The racks for the 55g’s and the 29g’s wee made from free pallets.
The 48” LED fixtures and almost all my AC filters came from a hobbyist shutting down his collection.
All my Zebra danios and my koi angels came from a local hobbyist who just enjoys giving them away.
The 10ft bench, 90g and 220g stands have cost me less than $100. $1.29-149 for cinder blocks and $3.88ea for 6 10ft 2x6.
My wife doesn’t mind me having multiple aquariums but she does periodically remind me how much I have spent so keeping the costs down promotes my scrounging.