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Huuuh, where to start? So, the prices here are, let's say, like in Croatia, in Zagreb. Some of them are lower, and some of them higher but nothing much, in general like in our country.
What to see? Make a list... Alfama and all the viewpoints around including Castelo de Sao Jorge, city center (Praça do Comércio, Baixa/Chaido, Miraduoro de Santa Catarina, Elevador Santa Justa ...), LX Factory, Belem, Sintra, Christo Rei, Cascais, Costa De Caparica... that are just highlights.

You must try bachalau (codefish) and pasteis de nata...

I don't know the prices of regular taxi, but Uber has quite fair price so try use Uber or just public transportation (1,5 euro). For longer distances see if you can find something cheap to rent or use the train.

Hope it helps... ;)

Thank you so much for help 😁

@gingergeorge is working in Lisaboa. Maybe he could be of help.

Thank you for help😁

taxi is very cheap, maybe the cheapest in europe, except when you catch it at the airport. be careful because there are some taxi drivers that are not as nice as you would like.
if you're going from airport to your hotel ask the hotel before you leave your home how much it is for the taxi run.
portuguese people anyway are extremely nice and polite and always ready for help and directions

https://www.smartertravel.com/2017/02/13/taxi-rip-offs-lisbon-warnings-dangers/

http://turismo.dnoticias.pt/artigo/5854-46-taxistas-aeroporto-lisboa-apanhados-enganar-turistas

edit: give a look here

https://lisbon-portugal-guide.com/lisbon-transport/lisbon-taxi-guide.html

Ginger George already gave you good hints.
I would add also the Gulbenkian Museum (the antique collection, leave the modern one) and the Museu do Oriente (really worth).
About the Pasteis de Nata you must absolutely have it at the Pateis de Belém close to the Jeronimos Monastery