What printer around 600€

[oxidized]

Just normal 3mm glass will work. Get it cut to the size of the print bed and use some gator clips to hold the glass. Then print out some glass holders for the corners of the bed.

I'm not sure those gator clips would fit between the actual bed and the moving platform, also, where would i secure those corner holders?

Now that I look at your pictures, it is going to be tough to get some gator clips on the bed. It does look like there is room between the bed and the frame it attaches to, to wedge a piece in to hold the glass. Don't forget to lower the bed the width of the glass so the nozzle doesn't hit.

Exactly