Opinions on buying my second polaroid

Hello everybody, I'm having some difficulty in making a decision so I would really appreciate your opinion on this: I have a polaroid now+ gen 2 and have shot some nice photos with it that I will post here soon but I want to take a step forwards.
I am in love with the SX70 for its design, its SLR nature and for the pictures that I see posted here.
I would love to learn how to use it, since it's a fully manual camera.
I found a model 1 in pretty good condition and tested for roughly 130euros on ebay, but I would have to get color 600 film which is more expensive and the ND filter, so I would probably spend a lot more money in the long run, not counting eventual problems that may arise from a 50 year old piece of tech.
The I-2 would be great but it's way out of my price range, and it's not an SLR which is something I think would benefit my image composition a lot.
Then my grandma lended me her 660 autofocus and i really liked it, but she wanted it back so it's not an option, but that made me curious for the new polaroid flip, that still isnt an SLR but the better flash, 4 focus lenses and sonar autofocus make it really interesting and cheaper in the long run for the I-type film. I found one online for 180 euros.

in a nutshell I'm kind of on a budget but

SX70 in good conditions for 130 euros with 600 film and cartdridge nd filter (not included)
or
Polaroid flip lightly used for 180 euros

I would really like the SLR and the manual controls but I'm kind of nervous for the (probably expensive) quirks of owning such an old camera.

People who tried both of them, please share your opinion on both the cameras and how they compare. I fell in love with these machines and would like to take a step forward in this world but I'm in need of some (a lot of ) guidance :)