Automatically selling at a target dollar price.

I would like to set up a tool, bot or whatever to support the following scenario/actions:

I buy coin A at 0.8$ (and whatever that is at the time in satoshi)

If coin A hits 1.2$ I want to automatically sell that for BTC and convert the BTC to Tether (USTD) (the automatic conversion to Tether is not a must, but would be neat).

I don't want to work with conditionals for example on bittrex because they are related to bitcoin prices and if bitcoin surges (such as now) conditionals set in the past might be way to high (or correct me if I got that wrong...).

I am using a set of exchanges such as bittrex, binance, hitbtc and so on, so ideally the solution should support a multitude of plattforms.

I am looking forward to your suggestions and support and I also wouldn't mind using a paid service since I am not that literate in writing scripts and the like.

PS.: I am aware that some will say that I should look at the bitcoin price in reference and not at the dollar price, I am happy to ignore these opportunity cost for now.