Came across the various diy spectrometer descriptions using DVDs as diffractors. Out of fun, I covered my cheap tablet camera with a piece of a DVD and took some pictures. Nothing is calibrated, just a colorful image and some profile plots (it’s all just fun for now):
t2b: 219B, SST-20, XP-L
What are you using (hard- and software) and how’s resolution and precision?
I have been looking for one of these things, but haven't found an affordable, but used, spectrometer.
The only one currently for sale on the busiest marketplace in the Netherlands is like $800..
It's actually a photography light meter including spectrometer functionality.
still a bit too pricey
I contemplated building a DIY spectrometer, but I wanted to derive actual tint, CRI etc too which implies that everything must be calibrated, not only the wavelength scale, but for every wavelength channel (camera pixel) the value must be separately calibrated to the correct radiant power. A DIY spectrometer does have a lot of value in giving insights in the shape of spectra though 
So I bought a ready-made one. My spectrometer is a small handheld one, Gossen Mavospec Base. The resolution is about 2nm and the precision is “very” (=summary of various specifications that determine precision )
I would not neccessarily recommend mine, there are spectrometers out there with better sounding specs that are cheaper. But who knows mine is more robust, no idea.
I’ve used their first version for some spectra I’ve posted here in the past.
They’re continually improving the design.
ColorMunki Photo is $200 or less used, cheapest factory option i’m aware of.
For software I used Argyll free desktop app for a while but ultimately paid $99 for convenience of ArgyllPRO android app.
They’re even widely available. Nice. Didn’t know this calibration tools contained full spectrometers, but that makes sense of course.
Xrite i1 PRO.
Mike
GETRAG MACBETH EYE-ONE PRO Spectrophotometer
For Lightroom/Photoshop digital imaging and display/printer color calibration.
X-rite i1 Pro