I don't spend a cent learning English but I've won million knowledge from them

Is the italic sentence in my conversation okay? If not, how would you rephrase it?

The following conversation took place in a chat room.

A: Silver, I think your spoken English is quite good. Have you ever studied abroad?
Silver: No. Many years ago I found a forum called UsingEnglish online and there were so many nice native speakers of English and they were professional English teachers. They've helped me with my English for many years. I'm still learning from some of them.
A: Wow, that's amazing. It's quite expensive to learn English in our city in some language schools. I spent 20,000 yuan for a year's course but I didn't learn anything. A friend of mine who studied abroad still can't speak fluent English. You're so lucky.
Silver: Yes, I am. I don't spend a cent learning English but I've won million knowledge from them.

Silverobama said:

I've won million knowledge from them.

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That does not work at all. How about I've learnt an enormous amount from them?

5jj said:

That does not work at all. How about I've learnt an enormous amount from them?

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That’s perfect, much appreciated.

Is the whole sentence good now?

I don't spend a cent learning English but I've learnt an enormous amount from them.

Silverobama said:

I don't spend a cent learning English but I've learnt an enormous amount from them.

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I find it odd that you chose "cent". You're in China and the forum is based in the UK. Neither country uses cents as currency. I'd go with "I spend nothing learning English but I've learnt an enormous amount from the members of that forum".