Dh and I left our children in October for 8 days. We were visiting Venezuela and contemplating a possible move to work there (decided no - too dangerous for our family) and needed the first visit to be just us.
Our children were 9y8m, 7y8m, 5y11m. They had 2 weekends (or parts therof) with a very close friend of the family, probably the closest I have to a sister (I have a sister ... lets not go there!) and someone they all love very much and who loves them (she will be their guardian if dh and I were to drop dead). They had the weekdays with Grannie, at Grannie's house.
I missed them like crazy, though I emailed and send pics every day and spoke twice on the phone (not easy due to time difference and cost, and unreliability of internet).
We've left them before for 4-5 days for short breaks, but never so young (think dd2 was 3 when I first left her for anything more than a weekend). I honestly would not, even now, go away for so long again until they are much older - and I'm talking about a 10yo now (and I am SOOOO not a precious mummy type!)
We didn't pay people as it was people doing it out of love, but we did provide lovely food in the fridge, a delivery of flowers to MIL, etc, so I can't help with the cost.
However, I cannot imagine leaving a child of 22 months with anyone other than Daddy, or possibly another blood relation, at this age. I'm quite tbh, and it takes a lot to shock me!