EDIT: This comment was incorrect and I do not wish for more down votes.

ORIGINAL: I believe it should be about 100 USD/hour for skilled consultant, but maybe someone with more experience can correct that.

For employment yes, consultant or contractor (which you probably will be if you're remote) can make double or more. 100 USD/hour is Prague, Czech Republic-level rate for a skilled consultant.

for these rates, how long would the contract be?

You mean in Prague? I don't have experience (by choice) with projects that span more than a year. I prefer to do several short term projects (~3-6 months) at a time.

wow that's awesome. In Canada, I haven't seen the rates that high for Canadian companies.. I guess I am not looking hard enough!

To be honest, I have never seen rates so high in Prague either. Very good offer for me would be 42 USD/hour for longer term project, 35 being more standard (yet still good). I currently live outside of Prague (regional city) and salary of employed developer (I know, not fair comparison) here are less than 14 USD/hour. Actually when I claimed I would not work for that much, I was told everyone wished for that kind of salary.

I should really look into what is to be known to get 100 USD/hour for medium term projects in Prague. I would be able to live from 2 to 3 month project for full year.

Employment is a whole different world because of various compulsory benefits, compensations for time not worked, much higher taxation etc.

You have to transform yourself into a consultant, being a contractor locks you into the rates you mentioned (the ceiling is around $50 to $70; big agencies are able to sell contractors to enterprises for around $80). It's not for everyone though, the rate is higher for a reason, you have to do a lot more things yourself and many devs don't enjoy doing them. Narrowing you specialization helps very much; it's also helpful to choose only a few (around 2) verticals (e.g. logistics, material production, ...) that you work in and mention that to everyone.

Depends on what contracting work you are doing. The average web/mobile dev can't charge that much anywhere in the US. Company that I work for itself (an app dev company) does not charge more than $120/hour/dev to their SF clients.