This project was probably inspired from the commercially available gadgets, I think there are great but don’t think they worth 100-200$. Now their are many alternatives, from old laptop displays to OLED screens, the presented project uses a small display similar to the Nokia display and a PIC micro controller, the authors made the entire project public including the schematic and pcb files in Eagle format.
The screen used is cheap since it is a copy of the Nokia display, they aquired it from Sparkfun, where you can find source code for different types of micro controllers, the pictures are stored in a microSD card, in the current firmware version are some limitations to the bitmap format and no subfolders are supported. The PIC device used has free C compiler support from Microchip, which is also a great thing if you want to improve the firmware.
The pcb is really compact but not overcrowded, it is possible to replicate with hobbyst equipment, it is a great middle-level project for you to thinker.
Digital picture frame: [Link]