You can try sodium alginate and some cost-effective crosslinker for hydrogel preparation. Sodium alginate and calcium chloride beads are commonly used for 3D culture studies.
Article Encapsulated human mesenchymal stem cells (eMSCs) as a novel...
I am using the Tissue Labs hydrogel. It is not as expensive as others on the market and there is availability to buy the hydrogel according to the tissue that will be studied.