Not long ago, I designed and built a low-cost DIY photo enlarger out of discarded boxes, a desk lamp, and a Mamiya Sekor lens. It cost me around S$50 (USD35) to build three prototypes. Cross my heart the prototype was more of a plaything device rather than a practical piece of darkroom equipment. I ended up assembling three prototypes before I felt I would develop the design to its full capacity. The third one worked pretty well and, I should say, the print results were acceptable by print sale standards.
(Such a shame I didn't take a photo of it.)
Anyway, I enjoyed watching these videos from YouTube by alwaysadventuring1 showing her DIY darkroom and photo enlarger. It goes to show that nothing can stop you from building your own darkroom. With or without a budget.