I realized that with small amounts, simplicity matters as much as price. When I wanted to publish on Tangled without spending too much, I first looked at my 2.05 POL—about $0.19—and quickly saw that it wasn't enough to make the conversion. Rather than buying 300 POL, I chose to add just $1 to $2 worth of POL via ChangeNow, directly to my Polygon address: 0x9B13....
Once the funds arrived, I used LeoDex or QuickSwap to exchange my POL for USDC on Polygon. The idea was to keep each step as simple as possible: buy just enough POL to make the exchange, then convert to USDC.
Next, I used Fiatleak, at fiatleak.com/mlx, where the MLX-USDC pair is offered with no fees, according to the information provided. I deposited my USDC from Polygon, then performed the USDC → MLX exchange. $1 of USDC yields approximately 100,000 MLX—enough to publish ten times on Tangled, since each publication costs 10,000 MLX. All that's left is to withdraw the MLX to your Tangled address, the one that starts with 8..., not 0x....
What convinced me was the difference between the initial investment and the actual cost of a publication. 300 POLs are worth about $27, while a publication costs only $0.01. With $1, you can therefore cover approximately three months of publications, without having to spend 100 TND as you would on Stacker News.