I considered constructing a jockey box but that got trumped by wanting a more enclosed system.
I looked around online for some ideas and found a few commercially available insulated coolers starting around $180. Too rich for my blood! in addition, those were typically not set up for a CO2 driven system but more towards a one-night keg killer party with a standard air tap.
As with most of my projects like this that drive my wife crazy, I talked about it for a few weeks, researched on the 'net, and had a fairly detailed plan in my head by the time I started buying materials.
Step 1: Materials
1. 55 Gallon Plastic Barrel (used) - $10
2. 30 Gallon Plastic Barrel (used) - $10
3. 4' x 8' x 2" Extruded Polystyrene Insulation - $28
4. Shower Drain + Reducer - $??
5. Misc PVC Fittings and pipe - left over from previous plumbing projects
6. PVC Ball Valve - $??
7. Thermos - $5
8. Casters (4) - $12
9. 4' x 8' x 1/2" Faced Insulation - $9
10. Can of "Great Stuff" - $6
11. 4" x 7/8" Corner Brace (2) - $5
12. Aluminum Tape, spray glue, plywood, screws, etc. - Extra stuff laying about
Grand Total = about $105 (figure $20 for the stuff that I don't recall the price)