If you didn't want to do the wire rack solution, which is both inexpensive and easy, and your basic carpentry skills are fair, it's pretty easy to build a system using 2x4s and 1x2s, similar to what BtM described.

The problem is that at a certain point your workload of cutting (not to mention fitting into a tighter space) can detract from the 'fun'. If you can find custom wire racks that will support the weight, you can save a TON of time going that route. Just be sure to keep those corks wet with either a tilted shelf or raised foot (and a 'stop' to prevent bottles sliding is never a bad idea either).

I had a small cellar in our last house, which was wonderful. I don't tend to keep 'vintages' (I like DRINKING my wine ), but sometimes if I find something wonderful but a touch young I'll lay a case or two by to cellar for a few years. '93 was a particularly AMAZING year (IMO) for Australian Shiraz, and we managed to keep the better part of a case of one of my favs for about 10yrs.