PI's are crazy prices right now as theres chip shortages, so theres simply less supply. And as the free market tells you, if you have less supply than you have demand, the price goes up.
Wish id known months ago as I had the chance to buy 100 Pi 4 8Gb in bulk, but passed it up. Would have made a great profit.
A Pi Pico has SPI lines, and they are readily available at cheapo price points - but ive never used them for SPI flashing. YMMV.
You can mod the ch341a if you are worried about voltage. heres the guide
https://www.youtube.com/watch?v=-ln3VIZKKaE
that being said, Ive never used a modded ch341a - I just use them as is. Every chip Ive ever flashed - countless x220/x230/t430/w530 using the clip as well as socketed DIP8s - with a standard ch341a has always been fine. I get there is a warning that there could be a problem, but ive never experienced anything breaking by using this programmer, in over half a decade of flashing chips. again, YMMV. i could just be miraculously lucky. Im also not too bothered if something does go ry as i have the kit to rework boards and replace chips. never had to though.
The one chip that didnt like it was a chip on the J4105 board from Asrock, for which I used a 1.8v converter and it worked fine
https://www.amazon.co.uk/DollaTek-adapter-motherboard-programmers-ezp2010/dp/B07DJ4X4MZ/r