Checked out your setup on aliexpress:
I could find the same LED strip that you used for 11 usr with free shipping - That would cut your setup down to an incredible 22 usd!
I would however need (at least) both connectors and a power supply:
LED-strip - Depending on colour, waterproof or not: 7.16-8.46 GBP (setup needs at least 2 of these)
Power-supply - Depending on amp output, but going for 5v, 6A: 7.16 GBP
JST-connectors - Going for 2 pairs: 3.71 GBP (5 pairs are only 4.33 GBP)
Total: Around 27 GBP (or 42 USD)
We still need something to connect the LEDs to the gpio - And I’m guessing this part still needs soldering? Or some other connecting wires?