How alternative do you wanna go? There is no 100% equivalent to a top class font for free, and I doubt there is a 90% one, whatever that might be. You might wanna read The value of type by Erik van Blokland and the FAQ on Free Fonts.

> a free alternative for Trinite No. 2

You’re kidding, right? This is like asking for a budget Rolls Royce. Sure, you can find a cheaper car, but the only resemblance will be that it also has four wheels and a steering wheel. You want a free alternative for Trinité No. 2? You will find a serif face that has an ’a’ and a ’b’ and a ’c’ and so on, but that’ll be the only thing similar.

If you need free fonts, there definitely is no room to be picky. Just use whatever you can find.

A free alternative to Trinité does not exist, as stated, but I think Dolly could be an excellent and relatively cheap alternative for it.