Your question will get better answers if you can answer some initial questions. What do you consider cheap? What wavelength range do you need to use? Do you plan to do reflectance or absorbance spectroscopy? What is the range of extinction coefficients for your materials? What concentration range do you need to get (assuming solution spectra)? What level of precision do you require?
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For serious work at low cost, one should consider a used professional spectrometer. I am working on an old Hitachi 100-80 double beam spectrophotometer with excellent optics. The cost of these will typically be a few hundred USD.