I built racks out of plywood and drywall screws.
Once they are full of wine (and there was no question mine were going to be FULL), you can't see what they are made of anyway (if the edges offend you, there is molding or paint as an alternative).
I just laid out a bunch of bottles and calculated the largest space a dozen bottles would need and built to suit, double depth as Roy suggests. Cheapest possibel way to house the most wine per cubic metre (foot, for you Yanks)
I think Jenise has been in my cellar - it holds a fair bit of wine, doesn't it.....
There are cooling units available in the $600 range that work reliably and that is a nice way to go if passive would result in too high summer temperatures, but do a realistic assessment of your wine storage needs. There is nothing at all wrong with conditions that slowly swing up to no more than 70 F. in the summer - your wine will simply mature a bit more quickly. Get higher and you are into territory where generally held opinion is that you will risk damage to the wine.
So if you get up to 70 deg. for 3 weeks in the worst of summer, no big deal and you can avoid buying a cooler.
And don't forget to insulate the ceiling - you can gain a lot of heat from that otherwise.
If you DO need a cooling unit I like the Canadian built Drobot - they market under Koolspace. They fit bewteen studs in a wall and if you have a handy space on the other side of the cellar wall, the heat pumped out of the cellar goes into the house to reduce your heating needs.