+ 1 on Puritan Ultimate (but maybe outside your price range unless you can find them used).
Also, Lavricables are thin and flexible. But super high quality.
Lavricables grand-30-core-silver-mains power
The Master line should be well within your desired price range. At shorter lengths, maybe even the Grand Line would still be in the range; it has even more conductors (30 vs 20) a bit thicker, but still very flexible i believe. I use the Master for a DAC; I’ve considered getting some Grands for amps, but have not pulled the trigger yet. (Been waiting for tariff situation to resolve.)

