Interesting, SophieR, because I found the opposite. you cannot really talk about dating sites without talking about the free-vs-paid gap. I judge dating sites almost entirely on whether it's worth paying for now. The honest tradeoff with dating sites are the catchment against convenience.
In practice, dating sites live or dies on how thin it gets outside cities. If the free-vs-paid gap is not sorted, dating sites will not go anywhere.
Most of the frustration with dating sites traces back to the paywall question.
Once I stopped worrying about how many people are actually near you, dating sites got a lot simpler.
Hope that gives you something usable for cheap dating sites a waste of time.
I ended up using have a look at DatingFly for exactly this side of dating sites.