geoffj's solution is probably the best bodge mentioned so far. A very large barrel of rainwater might even do the job as a heat sink rather than having it pass through an electric fridge.
Put a zigzag of pipework behind your wine store. Copper would be best, but the stuff you get for solar thermal heating doesn't look like copper, so whatever that stuff is would probably work well enough. Run this through a pump (not much power required) and into a large coil of pipe dropped into a big rainwater barrel kept in a shady place. if you can partially bury it, even better.
Ideally, stick some basic controls on the pump so that it only operates during the day, or for 10 minutes every hour, or whenever the temperature gets too high.
A really bodgy bodge might just be to have the aforementioned big rainwater barrel, drop a submersible pump into it, run water through a coil behind your wine, then drop it back into the barrel. This would definitely have to be run on some kind of timer or thermostat.
Might work, might not. Don't know if a rainwater barrel would have enough thermal mass. Insulate the barrel as much as possible.
EDIT: I'd suggest that bodging it from an old fridge is a non-starter. Getting hold of the extra coolant required is probably going to be a pain and you'd have to massively extend everything so that the heat could be dumped outside. Otherwise, it would be equivalent to having a fridge with an open door, which over time just makes the whole room warmer, az any ful kno.