Soldato
That's what I'd do too. A 1050ti uses hardly any power that even OP psu will have no issue running it. I even have a 480 running on a cheap antec 500w power supply and that card uses more power plus the system has 7 external hard drives and there's no issue at all.
I wouldn't get the 1050ti. I would get a 1060 and get a PSU later if needed. That's just me though.
Black Friday is coming up, so you might get a good deal on a GPU or PSU near the end of the month. It might be worth waiting a couple of weeks to see.