Agree here, I'd fire up ntop for small load clients and myself occasionally to grab netflow off my home gateway when weird things happen. You could always run in a cloud like digitalocean, but don't know of anyone doing hosted/saas solutions for any netflow tools. I'm interested in feedback here too if you find something...
*Good* + affordable netflow tools I find are sorely lacking out there, even ntop (2.x) is steering netflow to be a cost feature, so you're stuck with old (and somewhat broken/unstable) ntop 1.x. There is flowtools and some others, but any time I looked at them, they required more elbow-grease than I was willing to commit to for personal use and/or customer implementations.
-mb