I have had my Nitty-Gritty 1.0 cleaner since 1985, and it still works fine. It doesn't do very much, other than provide a platorm for manual brushing, and sucking.
Here's an internet picture of one:
It's very basic and not very attractive. As you can see, it sucks from underneath the record, so you have to apply the fluid, spread it, scrub, soak, and then turn it over to remove the fluid. And there's no turntable motor, you must rotate the record by hand.
Still, the results are quite good.
If it ever dies, I'll replace it with an Okki Nokki or ProJect unit. But it steadfastly refuses to fail. In the 37 years I've owned the unit, I've only had to replace the lip gasket twice, and the center clamp once.
The current production Record Doctor machine is based on Nitty-Gritty "technology", and is probably the cheapest entry point into a proper vacuum cleaner. Compared to the motor-driven cleaners, it's a trade-off of price vs. convenience.