@jk I'd probably go for a "cheers for that" than anything more effusive
comes across as more "yes, you took time out of your day to help out, thanks for that, here is an acknowledgement" than "oh thank you thank you kind person you're wonderful and thank you so much for helping me!" which always sounds somewhat disingenuous to me
@jk it's like saying "cheers, drive" to the bus driver, they were going to do it anyway but you happen to have been helped out by their actions