What HP calculator should I buy

[pier4r]

The problem for me is that if I have another working device it has to have a role.

Even "backup device" is a role.

Therefore, given math needs (although sometimes simple)
the ti34 at least is used for quick checks on the expenses with the stats mode.
The sharp el506w when the ti34 cannot help quickly.
The 50g (two of them) for new RPL and userRPL programs.
The hp prime when the 50g has not enough memory.

Ti nspire (handheld version)? I wanted to use lua but, well, failed. It is possible to use lua but there is a lot of overhead if one does not have the TI software. Maybe I have to check if I can put ndless on it.

Ti89. I know it can be useful, but I have not yet time for it. Although it is a nice memory from a colleague at the uni.

Free42: sometimes useful on the phone for quick checks (like the ti34), although when possible I use real calculators due to a proper keyboard.

And maybe I even forget some device. I'll have to check at home.

My point is that finding another useful role for another calculator is difficult. Indeed I have already the nspire and the ti89 practically unused.