For everything I spent < $250.
Melamine: $50
Melamine Edging:
Tile: $10
Glass: $80 (You can probably get this much cheaper)
Vents: $20
Lights: $15
Hinges: $7.50
Glass lock: $20
Total: $222.50 - I'm sure there are a few items that I left off (screws, screw caps, etc.).
One warning if you use melamine is that it is very very heavy. I had my brother come over to help me carry it from the basement to the second floor and we were both sweating by the time we got it upstairs.
I'm sure you could make something like this for much much cheaper, if you use white melamine from Home Depot, it will be about $12 cheaper and you don't have to order the edge band off the internet, they usually stock it. I'm sure there are other methods of locking the glass also (or you could do sliding doors, which is undoubtedly cheaper, but something I wanted to avoid) that are cheaper.
Let me know if you have any questions I'd be more than happy to help