I know it's a very open question. It's for a paper. So as a reference I'm looking maybe for the average density of insulin receptors per cell of a human tissue. I want to compare it to the density of MC1R (around 1000 per cell) and it says that's a low amount.
It would depend on the type of tissue. But if you are interested in any tissue, then have a look at this BioNumbers entry. It says that there are 100000 insulin receptors per cell in rat adipose tissue. Divide it by the surface area of the cell and you'll get the density. Cell dimensions can also be found in BioNumbers