Last year I bough "Irefox 27.5 aluminium frame" on Aliexpress for my GF, size M was the only one available.
My GF is 164cm and it fits her fine, but for a smaller person, maybe you would need something smaller.
Frame cost me $135 delivered.
I used some spare parts, that were laying around my house, to build the bike, and it ended up looking really nice.
And which is most important, GF likes it a lot...
Frame is built very well, especially considering the price.
Only downside, no holes for the bottlecage... which I later solved by drilling some holes and placing rivet nuts in the downtube.
Later I also found a cheap set of 160mm cranks and that made a big difference for her comfort.