How valuable is my Steam acc?

This sounds a bit suspicious

Take the sale value of all the games you own and add them up. Detract whatever % you think fair depending on various negatives related to your account. Add whatever % you think fair depending on various positives related to your account.

Now you got a number. Take 5% of that number. If the number is under 100$ then your account is worth nothing. If it's higher then you might be able to get 20-50 bucks for it.

~$50