I got my pvc from a sign company, as none of the stores around me carried it at the time. A week after my rack was done, they got it in stock. Go figure. I built my rack with three shelves. I have a picture of it in the DIY section if you want to search under my name. It's about 28" wide, 28" tall, and 17" deep, I think. I found some tubs at walmart and found I could put two 15qt tubs per shelf, or one 32qt tub per shelf, longways. So, assuming you want a similar rack, you can build it out of one 4'x8' sheet.
Here is a ballpark idea on costs... assuming you have nothing:
1. Circular saw: $50
2. Saw blade: $10
3. 1 Sheet of melamine: $30
4. 1 sheet of PVC - $57
5. 1 lb Box of screws - $5
6. Tubs - Less than $5 each
You'll also need a straight-edge and/or level, a pencil, and a drill and bit for predrilling your holes.