US versus EU servers as far as server content goes will be the same thing.
thisusernameistaken
Astraweb is the same exact servers as Newshosting that you glowingly recommended up thread. cant be that bad i guess. ;)
that map is a bit out of date but also doesnt show all the sellers. this might show things better, https://whatsmyuse.net/
blocknews, frugal usenet and usenetnow take cash in the mail, an option at checkout. maybe others will but they dont make it obvious so you would have to contact them directly. but honestly i wouldnt worry aboutr using your card. paying for usenet access is just as legal as paying for isp access.
i dont think any service is going to give you free weeks or a month with no strings attached. if they did everybody would use them and not pay. you can just buy 1 unlimited month of frugal usenet for 5 bucks (not a subscription) and call it good.
there are plenty of newshosting resellers that use the same exact servers that are much cheaper than $15 a month or even $10 a month. use one of the backbone maps to see all of the various ones.